centrin; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  26 RKKSGPKFELSEAQKCDIKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDCSGRIAFNVFLQLMTI 105
Cdd:PTZ00183   2 RKRRSERPGLTEDQKKEIREAFDLFDTDGSGTIDPKELKVAMRSLGFEPKKEEIKQMIADVDKDGSGKIDFEEFLDIMTK 81

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 442628888 106 KMAEKDTKEEILKAFRLFDDDDTGKISFRNLKRVARELGETLTDEELREMIDEADLDNDGEVNQEEFLRIMKKTSLY 182
Cdd:PTZ00183  82 KLGERDPREEILKAFRLFDDDKTGKISLKNLKRVAKELGETITDEELQEMIDEADRNGDGEISEEEFYRIMKKTNLF 158

centrin; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  26 RKKSGPKFELSEAQKCDIKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDCSGRIAFNVFLQLMTI 105
Cdd:PTZ00183   2 RKRRSERPGLTEDQKKEIREAFDLFDTDGSGTIDPKELKVAMRSLGFEPKKEEIKQMIADVDKDGSGKIDFEEFLDIMTK 81

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 442628888 106 KMAEKDTKEEILKAFRLFDDDDTGKISFRNLKRVARELGETLTDEELREMIDEADLDNDGEVNQEEFLRIMKKTSLY 182
Cdd:PTZ00183  82 KLGERDPREEILKAFRLFDDDKTGKISLKNLKRVAKELGETITDEELQEMIDEADRNGDGEISEEEFYRIMKKTNLF 158

Ca2+-binding protein, EF-hand superfamily [Signal transduction mechanisms];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  37 EAQKCDIKEAFDLFDNEGTGYIEVKELKVAIRALgfepkkeeIKRMISDIDKDCSGRIAFNVFLQLMTiKMAEKDTKEEI 116
Cdd:COG5126    1 DLQRRKLDRRFDLLDADGDGVLERDDFEALFRRL--------WATLFSEADTDGDGRISREEFVAGME-SLFEATVEPFA 71

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 442628888 117 LKAFRLFDDDDTGKISFRNLKRVARELGetLTDEELREMIDEADLDNDGEVNQEEFLRIMKK 178
Cdd:COG5126   72 RAAFDLLDTDGDGKISADEFRRLLTALG--VSEEEADELFARLDTDGDGKISFEEFVAAVRD 131

EF-hand, calcium binding motif; EF-hands are calcium-binding motifs that occur at least in pairs. Links between disease states and genes encoding EF-hands, particularly the S100 subclass, are emerging. Each motif consists of a 12 residue loop flanked on either side by a 12 residue alpha-helix. EF-hands undergo a conformational change unpon binding calcium ions.

                           10        20
                   ....*....|....*....|....*....
gi 442628888   151 ELREMIDEADLDNDGEVNQEEFLRIMKKT 179
Cdd:smart00054   1 ELKEAFRLFDKDGDGKIDFEEFKDLLKAL 29

centrin; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  26 RKKSGPKFELSEAQKCDIKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDCSGRIAFNVFLQLMTI 105
Cdd:PTZ00183   2 RKRRSERPGLTEDQKKEIREAFDLFDTDGSGTIDPKELKVAMRSLGFEPKKEEIKQMIADVDKDGSGKIDFEEFLDIMTK 81

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 442628888 106 KMAEKDTKEEILKAFRLFDDDDTGKISFRNLKRVARELGETLTDEELREMIDEADLDNDGEVNQEEFLRIMKKTSLY 182
Cdd:PTZ00183  82 KLGERDPREEILKAFRLFDDDKTGKISLKNLKRVAKELGETITDEELQEMIDEADRNGDGEISEEEFYRIMKKTNLF 158

EF-hand, calcium binding motif; A diverse superfamily of calcium sensors and calcium signal modulators; most examples in this alignment model have 2 active canonical EF hands. Ca2+ binding induces a conformational change in the EF-hand motif, leading to the activation or inactivation of target proteins. EF-hands tend to occur in pairs or higher copy numbers.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 442628888 115 EILKAFRLFDDDDTGKISFRNLKRVARELGETLTDEELREMIDEADLDNDGEVNQEEFLRIMK 177
Cdd:cd00051    1 ELREAFRLFDKDGDGTISADELKAALKSLGEGLSEEEIDEMIREVDKDGDGKIDFEEFLELMA 63

EF-hand, calcium binding motif; A diverse superfamily of calcium sensors and calcium signal modulators; most examples in this alignment model have 2 active canonical EF hands. Ca2+ binding induces a conformational change in the EF-hand motif, leading to the activation or inactivation of target proteins. EF-hands tend to occur in pairs or higher copy numbers.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 442628888  42 DIKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDCSGRIAFNVFLQLMT 104
Cdd:cd00051    1 ELREAFRLFDKDGDGTISADELKAALKSLGEGLSEEEIDEMIREVDKDGDGKIDFEEFLELMA 63

EF-hand domain pair;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 442628888  113 KEEILKAFRLFDDDDTGKISFRNLKRVAR--ELGETLTDEELREMIDEADLDNDGEVNQEEFLRIMK 177
Cdd:pfam13499   1 EEKLKEAFKLLDSDGDGYLDVEELKKLLRklEEGEPLSDEEVEELFKEFDLDKDGRISFEEFLELYS 67

Penta-EF hand, calcium binding motifs, found in Group I PEF proteins; The family corresponds to Group I PEF proteins that have been found not only in higher animals but also in lower animals, plants, fungi and protists. Group I PEF proteins include apoptosis-linked gene 2 protein (ALG-2), peflin and similar proteins. ALG-2, also termed programmed cell death protein 6 (PDCD6), is a widely expressed calcium-binding modulator protein associated with cell proliferation and death, as well as cell survival. It forms a homodimer in the cell or a heterodimer with its closest paralog peflin. Among the PEF proteins, ALG-2 can bind three Ca2+ ions through its EF1, EF3, and EF5 hands, where it is unique in that its EF5 hand binds Ca2+ ion in a canonical coordination. Peflin is a ubiquitously expressed 30-kD PEF protein containing five EF-hand motifs in its C-terminal domain and a longer N-terminal hydrophobic domain (NHB domain) than any other member of the PEF family. The NHB domain harbors nine repeats of a nonapeptide (A/PPGGPYGGP). Peflin may modulate the function of ALG-2 in Ca2+ signaling. It exists only as a heterodimer with ALG-2, and binds two Ca2+ ions through its EF1 and EF3 hands. Its additional EF5 hand is unpaired and does not bind Ca2+ ion but mediates the heterodimerization with ALG-2. The dissociation of heterodimer occurs in the presence of Ca2+.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  42 DIKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEE-IKRMISDIDKDCSGRIAFNVFLQLMTIKMAEKdtkeeilKAF 120
Cdd:cd16180    1 ELRRIFQAVDRDRSGRISAKELQRALSNGDWTPFSIEtVRLMINMFDRDRSGTINFDEFVGLWKYIQDWR-------RLF 73

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 442628888 121 RLFDDDDTGKISFRNLKRVARELGETLTDEELREMIDEADLDNDGEVNQEEFLRIM 176
Cdd:cd16180   74 RRFDRDRSGSIDFNELQNALSSFGYRLSPQFVQLLVRKFDRRRRGSISFDDFVEAC 129

Penta-EF hand, calcium binding motifs, found in Group I PEF proteins; The family corresponds to Group I PEF proteins that have been found not only in higher animals but also in lower animals, plants, fungi and protists. Group I PEF proteins include apoptosis-linked gene 2 protein (ALG-2), peflin and similar proteins. ALG-2, also termed programmed cell death protein 6 (PDCD6), is a widely expressed calcium-binding modulator protein associated with cell proliferation and death, as well as cell survival. It forms a homodimer in the cell or a heterodimer with its closest paralog peflin. Among the PEF proteins, ALG-2 can bind three Ca2+ ions through its EF1, EF3, and EF5 hands, where it is unique in that its EF5 hand binds Ca2+ ion in a canonical coordination. Peflin is a ubiquitously expressed 30-kD PEF protein containing five EF-hand motifs in its C-terminal domain and a longer N-terminal hydrophobic domain (NHB domain) than any other member of the PEF family. The NHB domain harbors nine repeats of a nonapeptide (A/PPGGPYGGP). Peflin may modulate the function of ALG-2 in Ca2+ signaling. It exists only as a heterodimer with ALG-2, and binds two Ca2+ ions through its EF1 and EF3 hands. Its additional EF5 hand is unpaired and does not bind Ca2+ ion but mediates the heterodimerization with ALG-2. The dissociation of heterodimer occurs in the presence of Ca2+.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  44 KEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDCSGRIAFNVFLQL-MTIKMaekdtkeeILKAFRL 122
Cdd:cd16180   70 RRLFRRFDRDRSGSIDFNELQNALSSFGYRLSPQFVQLLVRKFDRRRRGSISFDDFVEAcVTLKR--------LTDAFRK 141

                         90
                 ....*....|.
gi 442628888 123 FDDDDTGKISF 133
Cdd:cd16180  142 YDTNRTGYATI 152

EF-hand, calcium binding motif, found in the hexa-EF hand proteins family; The hexa-EF hand proteins family, also named the calbindin sub-family, contains a group of six EF-hand Ca2+-binding proteins, including calretinin (CR, also termed 29 kDa calbindin), calbindin D28K (CB, also termed vitamin D-dependent calcium-binding protein, avian-type), and secretagogin (SCGN). CR is a cytosolic hexa-EF-hand calcium-binding protein predominantly expressed in a variety of normal and tumorigenic t-specific neurons of the central and peripheral nervous system. It is a multifunctional protein implicated in many biological processes, including cell proliferation, differentiation, and cell death. CB is highly expressed in brain tissue. It is a strong calcium-binding and buffering protein responsible for preventing a neuronal death as well as maintaining and controlling calcium homeostasis. SCGN is a six EF-hand calcium-binding protein expressed in neuroendocrine, pancreatic endocrine and retinal cells. It plays a crucial role in cell apoptosis, receptor signaling and differentiation. It is also involved in vesicle secretion through binding to various proteins, including interacts with SNAP25, SNAP23, DOC2alpha, ARFGAP2, rootletin, KIF5B, beta-tubulin, DDAH-2, ATP-synthase and myeloid leukemia factor 2. SCGN functions as a Ca2+ sensor/coincidence detector modulating vesicular exocytosis of neurotransmitters, neuropeptides or hormones. Although the family members share a significant amount of secondary sequence homology, they display altered structural and biochemical characteristics, and operate in distinct fashions. CB contains six EF-hand motifs in a single globular domain, where EF-hands 1, 3, 4, 5 bind four calcium ions. CR contains six EF-hand motifs within two independent domains, CR I-II and CR III-VI. They harbor two and four EF-hand motifs, respectively. The first 5 EF-hand motifs are capable of binding calcium ions, while the EF-hand 6 is inactive. SCGN consists of the three globular domains each of which contains a pair of EF-hand motifs. Human SCGN simultaneously binds four calcium ions through its EF-hands 3, 4, 5 and 6 in one high affinity and three low affinity calcium-binding sites. In contrast, SCGNs in other lower eukaryotes, such as D. rerio, X. laevis, M. domestica, G. gallus, O. anatinus, are fully competent in terms of six calcium-binding.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  45 EAFDLFDNEGTGYIEVKELKVAIRAL-----GFEPKKEEI----KRMISDIDKDCSGRIAFNVFLQLMTIK--------- 106
Cdd:cd15902    3 EVWMHFDADGNGYIEGKELDSFLRELlkalnGKDKTDDEVaekkKEFMEKYDENEDGKIEIRELANILPTEenflllfrr 82

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 442628888 107 MAEKDTKEEILKAFRLFDDDDTGKISFRNLKRVAREL--------GETLTDEELREMIDEADLDNDGEVNQEEFLRIM 176
Cdd:cd15902   83 EQPLISSVEFMKIWRKYDTDGSGFIEAKELKGFLKDLllknkkhvSPPKLDEYTKLILKEFDANKDGKLELDEMAKLL 160

EF-hand motif found in eukaryotic phosphoinositide-specific phospholipase C (PI-PLC, EC 3.1.4.11) isozymes; PI-PLC isozymes are signaling enzymes that hydrolyze the membrane phospholipids phosphatidylinositol-4,5-bisphosphate (PIP2) to generate two important second messengers in eukaryotic signal transduction cascades, Inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). InsP3 triggers inflow of calcium from intracellular stores, while DAG, together with calcium, activates protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity. Calcium is required for the catalysis. This family corresponds to the four EF-hand motifs containing PI-PLC isozymes, including PI-PLC-beta (1-4), -gamma (1-2), -delta (1,3,4), -epsilon (1), -zeta (1), eta (1-2). Lower eukaryotes such as yeast and slime molds contain only delta-type isozymes. In contrast, other types of isoforms present in higher eukaryotes. This family also includes 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase 1 (PLC1) from fungi. Some homologs from plants contain only two atypical EF-hand motifs and they are not included. All PI-PLC isozymes except sperm-specific PI-PLC-zeta share a core set of domains, including an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core, and a single C2 domain. PI-PLC-zeta lacks the PH domain. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. Most of EF-hand motifs found in PI-PLCs consist of a helix-loop-helix structure, but lack residues critical to metal binding. Moreover, the EF-hand region of most of PI-PLCs may have an important regulatory function, but it has yet to be identified. However, PI-PLC-zeta is a key exception. It is responsible for Ca2+ oscillations in fertilized oocytes and exhibits a high sensitivity to Ca2+ mediated through its EF-hand domain. In addition, PI-PLC-eta2 shows a canonical EF-loop directing Ca2+-sensitivity and thus can amplify transient Ca2+ signals. Also it appears that PI-PLC-delta1 can regulate the binding of PH domain to PIP2 in a Ca2+-dependent manner through its functionally important EF-hand domains. PI-PLCs can be activated by a variety of extracellular ligands, such as growth factors, hormones, cytokines and lipids. Their activation has been implicated in tumorigenesis and/or metastasis linked to migration, proliferation, growth, inflammation, angiogenesis and actin cytoskeleton reorganization. PI-PLC-beta isozymes are activated by G-protein coupled receptor (GPCR) through different mechanisms. However, PI-PLC-gamma isozymes are activated by receptor tyrosine kinase (RTK), such as Rho and Ras GTPases. In contrast, PI-PLC-epsilon are activated by both GPCR and RTK. PI-PLC-delta1 and PLC-eta 1 are activated by GPCR-mediated calcium mobilization. The activation mechanism for PI-PLC-zeta remains unclear.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  43 IKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDCSGRIAFNVFLQLMTIKMaekdTKEEILKAFRL 122
Cdd:cd15898    2 LRRQWIKADKDGDGKLSLKEIKKLLKRLNIRVSEKELKKLFKEVDTNGDGTLTFDEFEELYKSLT----ERPELEPIFKK 77

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 442628888 123 FDDDDTGKISFRNLKRVAR-ELGETLTDEELREMIDEADLD-NDGEVNQEEFLRIM 176
Cdd:cd15898   78 YAGTNRDYMTLEEFIRFLReEQGENVSEEECEELIEKYEPErENRQLSFEGFTNFL 133

N-terminal domain of Myosin essential light chain ELC; ELC is part of the apicomplexan membrane-associated protein complex called the glideosome, which is essential for parasite motility. The glideosome is composed of six proteins: myosin A (MyoA), essential light chain ELC, myosin light chain MLC1 (also called MTIP), and the glideosome-associated proteins GAP40, GAP45, and GAP50. MyoA is a Class XIV myosin implicated in gliding motility, as well as host cell and tissue invasion by parasites. ELC binds to the MyoA neck region adjacent to the MLC1-binding site, and both myosin light chains co-located to the glideosome. Although ELCs bind to a conserved MyoA sequence, P. falciparum ELC adopts a distinct structure in the free and MyoA-bound state. Therefore ELCs enhance MyoA performance by inducing alpha helical structure formation in MyoA and thus stiffening its lever arm. It has been shown that disruption of MyoA, MLC1, or ELC have dramatic effects on parasite motility but do not affect parasite shape or replication. The ELC N-terminal domain is part of the EF-hand calcium binding motif superfamily. Calcium binding has no effect on the structure of ELCs.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 442628888  43 IKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDcsgriafnVFLQLMTIKMAEKD 111
Cdd:cd22949    5 FREAFILFDRDGDGELTMYEAVLAMRSCGIPLTNDEKDALPASMNWD--------QFENWAKKKLAYSD 65

EF-hand motif found in eukaryotic phosphoinositide-specific phospholipase C (PI-PLC, EC 3.1.4.11) isozymes; PI-PLC isozymes are signaling enzymes that hydrolyze the membrane phospholipids phosphatidylinositol-4,5-bisphosphate (PIP2) to generate two important second messengers in eukaryotic signal transduction cascades, Inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). InsP3 triggers inflow of calcium from intracellular stores, while DAG, together with calcium, activates protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity. Calcium is required for the catalysis. This family corresponds to the four EF-hand motifs containing PI-PLC isozymes, including PI-PLC-beta (1-4), -gamma (1-2), -delta (1,3,4), -epsilon (1), -zeta (1), eta (1-2). Lower eukaryotes such as yeast and slime molds contain only delta-type isozymes. In contrast, other types of isoforms present in higher eukaryotes. This family also includes 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase 1 (PLC1) from fungi. Some homologs from plants contain only two atypical EF-hand motifs and they are not included. All PI-PLC isozymes except sperm-specific PI-PLC-zeta share a core set of domains, including an N-terminal pleckstrin homology (PH) domain, four atypical EF-hand motifs, a PLC catalytic core, and a single C2 domain. PI-PLC-zeta lacks the PH domain. The PLC catalytic core domain is a TIM barrel with two highly conserved regions (X and Y) split by a highly degenerate linker sequence. Most of EF-hand motifs found in PI-PLCs consist of a helix-loop-helix structure, but lack residues critical to metal binding. Moreover, the EF-hand region of most of PI-PLCs may have an important regulatory function, but it has yet to be identified. However, PI-PLC-zeta is a key exception. It is responsible for Ca2+ oscillations in fertilized oocytes and exhibits a high sensitivity to Ca2+ mediated through its EF-hand domain. In addition, PI-PLC-eta2 shows a canonical EF-loop directing Ca2+-sensitivity and thus can amplify transient Ca2+ signals. Also it appears that PI-PLC-delta1 can regulate the binding of PH domain to PIP2 in a Ca2+-dependent manner through its functionally important EF-hand domains. PI-PLCs can be activated by a variety of extracellular ligands, such as growth factors, hormones, cytokines and lipids. Their activation has been implicated in tumorigenesis and/or metastasis linked to migration, proliferation, growth, inflammation, angiogenesis and actin cytoskeleton reorganization. PI-PLC-beta isozymes are activated by G-protein coupled receptor (GPCR) through different mechanisms. However, PI-PLC-gamma isozymes are activated by receptor tyrosine kinase (RTK), such as Rho and Ras GTPases. In contrast, PI-PLC-epsilon are activated by both GPCR and RTK. PI-PLC-delta1 and PLC-eta 1 are activated by GPCR-mediated calcium mobilization. The activation mechanism for PI-PLC-zeta remains unclear.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 442628888 116 ILKAFRLFDDDDTGKISFRNLKRVARELGETLTDEELREMIDEADLDNDGEVNQEEFLRIMKK 178
Cdd:cd15898    2 LRRQWIKADKDGDGKLSLKEIKKLLKRLNIRVSEKELKKLFKEVDTNGDGTLTFDEFEELYKS 64

EF-hand, calcium binding motif, found in Drosophila melanogaster calbindin-32 (CBN) and similar proteins; CBN, the product of the cbn gene, is a Drosophila homolog to vertebrate neuronal six EF-hand calcium binding proteins. It is expressed through most of ontogenesis with a selective distribution in the nervous system and in a few small adult thoracic muscles. Its precise biological role remains unclear. CBN contains six EF-hand motifs, but some of them may not bind calcium ions due to the lack of key residues.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  49 LFDNEGTGYIEVKELKVAIRALGFEPKKEEIKR----------MISDIDKDCSGRIAFNVFLQLMTIKM----------A 108
Cdd:cd16179  103 EYDKDNSGYIEADELKNFLKHLLKEAKRDNDVSedklieytdtILQLFDRNKDGKLQLSEMARLLPVKEnflcrpifkgA 182

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 442628888 109 EKDTKEEILKAFRLFDDDDTGKISFRNLKRVARELGETLTD-------EELREMI-DEADLDNDGEVNQEE 171
Cdd:cd16179  183 GKLTREDIDRVFALYDRDNNGTIENEELTGFLKDLLELVQEdydeqdlEEFKEIIlRGWDFNNDGKISRKE 253

EF-hand, calcium binding motif, found in calbindin (CB); CB, also termed calbindin D28, or D-28K, or avian-type vitamin D-dependent calcium-binding protein, is a unique intracellular calcium binding protein that functions as both a calcium sensor and buffer in eukaryotic cells, which undergoes a conformational change upon calcium binding and protects cells against insults of high intracellular calcium concentration. CB is highly expressed in brain and sensory neurons. It plays essential roles in neural functioning, altering synaptic interactions in the hippocampus, modulating calcium channel activity, calcium transients, and intrinsic neuronal firing activity. It prevents a neuronal death, as well as maintains and controls calcium homeostasis. CB also modulates the activity of proteins participating in the development of neurodegenerative disorders such as Alzheimer's disease, Huntington's disease, and bipolar disorder. Moreover, CB interacts with Ran-binding protein M, a protein known to involve in microtubule function. It also interacts with alkaline phosphatase and myo-inositol monophosphatase, as well as caspase 3, an enzyme that plays an important role in the regulation of apoptosis. CB contains six EF-hand motifs in a single globular domain, where EF-hands 1, 3, 4, 5 bind four calcium ions with high affinity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  45 EAFDLFDNEGTGYIEVKELKVAIRALGFEPKK------EEIKRMISDIDKDCSGRIAFNVFLQLMTIK-------MAEKD 111
Cdd:cd16176    3 EIWHHYDNDGNGYIEGKELQSFIQELQQARKKaglelsDQMKAFVDQYGQSTDGKIGIVELAQILPTEenfllffRQQLK 82

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 442628888 112 TKEEILKAFRLFDDDDTGKISFRNLKRVAREL--------GETLTDEELREMIDEADLDNDGEVNQEEFLRIM 176
Cdd:cd16176   83 SSEEFMQTWRKYDADHSGFIEADELKSFLKDLlkkankpfDESKLEEYTHTMLKMFDSNNDGKLGLTEMARLL 155

EF-hand, calcium binding motif, found in uncharacterized calglandulin-like proteins; The family corresponds to a group of uncharacterized calglandulin-like proteins. Although their biological function remain unclear, they show high sequence similarity with human calglandulin-like protein GAGLP, which is an ortholog of calglandulin from the venom glands of Bothrops insularis snake. Both GAGLP and calglandulin are putative Ca2+-binding proteins with four EF-hand motifs. However, members in this family contain only three EF-hand motifs. In this point, they may belong to the parvalbumin-like EF-hand family, which is characterized by the presence of three consecutive EF-hand motifs (helix-loop-helix).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 442628888  32 KFELSEAQKCDIKEAFDLFDNEGTGYIEVKELKVAIRAL----GFEP-KKEEIKRMISDIDKDCSGRIAFNVFLQLMT 104
Cdd:cd16252   28 KFQTSEQQEEAIRKAFQMLDKDKSGFIEWNEIKYILSTVpssmPVAPlSDEEAEAMIQAADTDGDGRIDFQEFSDMVK 105

EF hand; The EF-hands can be divided into two classes: signalling proteins and buffering/transport proteins. The first group is the largest and includes the most well-known members of the family such as calmodulin, troponin C and S100B. These proteins typically undergo a calcium-dependent conformational change which opens a target binding site. The latter group is represented by calbindin D9k and do not undergo calcium dependent conformational changes.

                          10        20
                  ....*....|....*....|....*....
gi 442628888  151 ELREMIDEADLDNDGEVNQEEFLRIMKKT 179
Cdd:pfam00036   1 ELKEIFRLFDKDGDGKIDFEEFKELLKKL 29

Eps15 homology domain; Pair of EF hand motifs that recognise proteins containing Asn-Pro-Phe (NPF) sequences.

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888   108 AEKDTKEEIlkaFRLFDDDDTGKISFRNLKRVARELGetLTDEELREMIDEADLDNDGEVNQEEFLRIMK 177
Cdd:smart00027   7 EDKAKYEQI---FRSLDKNQDGTVTGAQAKPILLKSG--LPQTLLAKIWNLADIDNDGELDKDEFALAMH 71

The penta-EF hand (PEF) family; The penta-EF hand (PEF) family contains a group of five EF-hand calcium-binding proteins, including several classical calpain large catalytic subunits (CAPN1, 2, 3, 8, 9, 11, 12, 13, 14), two calpain small subunits (CAPNS1 and CAPNS2), as well as non-calpain PEF proteins, ALG-2 (apoptosis-linked gene 2, also termed programmed cell death protein 6, PDCD6), peflin, sorcin, and grancalcin. Based on the sequence similarity of EF1 hand, ALG-2 and peflin have been classified into group I PEF proteins. Calcium-dependent protease calpain subfamily members, sorcin and grancalcin, are group II PEF proteins. Calpains (EC 3.4.22.17) are calcium-activated intracellular cysteine proteases that play important roles in the degradation or functional modulation in a variety of substrates. They have been implicated in a number of physiological processes such as cell cycle progression, remodeling of cytoskeletal-cell membrane attachments, signal transduction, gene expression and apoptosis. ALG-2 is a pro-apoptotic factor that forms a homodimer in the cell or a heterodimer with its closest paralog peflin through their EF5s. Peflin is a 30-kD PEF protein with a longer N-terminal hydrophobic domain than any other member of the PEF family, and it contains nine nonapeptide (A/PPGGPYGGP) repeats. It exists only as a heterodimer with ALG-2. The dissociation of heterodimer occurs in the presence of Ca2+. ALG-2 interacts with various proteins in a Ca2+-dependent manner. Sorcin (for soluble resistance-related calcium binding protein) is a soluble resistance-related calcium-binding protein that participates in the regulation of calcium homeostasis in cells. Grancalcin is a cytosolic Ca2+-binding protein specifically expressed in neutrophils and monocytes/macrophages. It plays a key role in leukocyte-specific functions that are responsible for host defense. Grancalcin can form a heterodimer together with sorcin. Members in this family contain five EF-hand motifs attached to an N-terminal region of variable length containing one or more short Gly/Pro-rich sequences. These proteins form homodimers or heterodimers through pairing between the 5th EF-hands from the two molecules. Unlike calmodulin, the PEF domains do not undergo major conformational changes upon binding Ca2+.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  42 DIKEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDcSGRIAFNVFLQLMtIKMaekdtkEEILKAFR 121
Cdd:cd15897   71 AWQEIFRTYDTDGSGTIDSNELRQALSGAGYRLSEQTYDIIIRRYDRG-RGNIDFDDFIQCC-VRL------QRLTDAFR 142

                         90
                 ....*....|..
gi 442628888 122 LFDDDDTGKISF 133
Cdd:cd15897  143 RYDKDQDGQIQV 154

Penta-EF hand, calcium binding motifs, found in sorcin; Sorcin, also termed 22 kDa Ca2+-binding protein, CP-22, or V19, is a soluble resistance-related calcium-binding protein that is expressed in normal mammalian tissues, such as the liver, lungs and heart. The up-regulation of sorcin is correlated with a number of cancer types, including colorectal, gastric and breast cancer. It may represent a therapeutic target for reversing tumor multidrug resistance (MDR). Sorcin participates in the regulation of calcium homeostasis in cells and is necessary for the activation of mitosis and cytokinesis. It enhances metastasis and promotes epithelial-to-mesenchymal transition of colorectal cancer. Moreover, sorcin has been implicated in the regulation of intracellular Ca2+ cycling and cardiac excitation-contraction coupling. It displays the anti-apoptotic properties via the modulation of mitochondrial Ca2+ handling in cardiac myocytes. It can target and activate the sarcolemmal Na+/Ca2+ exchanger (NCX1) in cardiac muscle. Meanwhile, sorcin modulates cardiac L-type Ca2+ current by functional interaction with the alpha1C subunit. It also associates with calcium/calmodulin-dependent protein kinase IIdeltaC (CaMKIIdelta(C)) and further modulates ryanodine receptor (RyR) function in cardiac myocytes. Furthermore, sorcin may act as a Ca2+ sensor for glucose-induced nuclear translocation and the activation of carbohydrate-responsive element-binding protein (ChREBP)-dependent genes. As a mitochondrial chaperone TRAP1 interactor, sorcin involves in mitochondrial metabolism through the TRAP1 pathway. In addition, sorcin may regulate the inhibition of type I interferon response in cells through interacting with foot-and-mouth disease virus (FMDV) VP1. Sorcin contains a flexible glycine and proline-rich N-terminal extension and five EF-hand motifs that associate with membranes in a calcium-dependent manner. It may harbor three potential Ca2+ binding sites through its EF1, EF2 and EF3 hands. However, binding of only two Ca2+/monomer suffices to trigger the conformational change that exposes hydrophobic regions and leads to interaction with the respective targets. Sorcin forms homodimers through the association of the unpaired EF5 hand. Among the PEF proteins, sorcin is unique in that it contains potential phosphorylation sites by cAMP-dependent protein kinase (PKA), and it can form a tetramer at slightly acid pH values although remaining a stable dimer at neutral pH.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  56 GYIEVKELKVAIR----ALGFEP-KKEEIKRMISDIDKDCSGRIAFNVFLQLMTIKMAEKdtkeeilKAFRLFDDDDTGK 130
Cdd:cd16187   14 GQIDADELQRCLTqsgiAGGYKPfNLETCRLMISMLDRDMSGTMGFNEFKELWAVLNGWR-------QHFISFDSDRSGT 86

                         90       100
                 ....*....|....*....|..
gi 442628888 131 ISFRNLKRVARELGETLTDEEL 152
Cdd:cd16187   87 VDPQELQKALTTMGFRLSPQAV 108

Penta-EF hand, calcium binding motifs, found in sorcin, grancalcin, and similar proteins; The family corresponds to the second group of penta-EF hand (PEF) proteins that includes sorcin, grancalcin, and similar proteins. Sorcin, also termed 22 kDa Ca2+-binding protein, CP-22, or V19, is a soluble resistance-related calcium-binding protein that is expressed in normal mammalian tissues, such as the liver, lungs and heart. It contains a flexible glycine and proline-rich N-terminal extension and five EF-hand motifs that associate with membranes in a calcium-dependent manner. It may harbor three potential Ca2+ binding sites through its EF1, EF2 and EF3 hands. However, binding of only two Ca2+/monomer suffices to trigger the conformational change that exposes hydrophobic regions and leads to interaction with the respective targets. Sorcin forms homodimers through the association of the unpaired EF5 hand. Among the PEF proteins, sorcin is unique in that it contains potential phosphorylation sites by cAMP-dependent protein kinase (PKA), and it can form a tetramer at slightly acid pH values although remaining a stable dimer at neutral pH. Grancalcin (GCA) is a cytosolic Ca2+-binding protein specifically expressed in neutrophils and monocytes/macrophages. It can strongly interact with sorcin to form a heterodimer and further modulate the function of sorcin. GCA exists as homodimers in solution. It contains five EF-hand motifs attached to an N-terminal region of an approximately 50 residue-long segment rich in glycines and prolines. In contrast with sorcin, GCA binds two Ca2+ ions through its EF1 and EF3 hands.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  56 GYIEVKELKVAIRALGF----EPKKEEIKR-MISDIDKDCSGRIAFNVFLQLMTIKMAEKDTkeeilkaFRLFDDDDTGK 130
Cdd:cd16181   14 GQIDADELQRCLTQSGIsgnyQPFSLETCRlMIAMLDRDHSGKMGFNEFKELWAALNQWKTT-------FMQYDRDRSGT 86

                         90       100
                 ....*....|....*....|....*.
gi 442628888 131 ISFRNLKRVARELGETLTDEELREMI 156
Cdd:cd16181   87 VEPQELQQAIRSFGYNLSPQALNVIV 112

Penta-EF hand, calcium binding motifs, found in PEF calpain family; The PEF calpain family belongs to the second group of penta-EF hand (PEF) proteins. It includes classical (also called conventional or typical) calpain (referring to a calcium-dependent papain-like enzymes, EC 3.4.22.17) large catalytic subunits (CAPN1, 2, 3, 8, 9, 11, 12, 13, 14) and two calpain small subunits (CAPNS1 and CAPNS2), which are largely confined to animals (metazoans). These PEF-containing are nonlysosomal intracellular calcium-activated intracellular cysteine proteases that play important roles in the degradation or functional modulation in a variety of substrates in response to calcium signalling. The classical mu- and m-calpains are heterodimers consisting of homologous but a distinct (large) L-subunit/chain (CAPN1 or CAPN2) and a common (small) S-subunit/chain (CAPNS1 or CAPNS2). These L-subunits (CAPN1 and CAPN2) and S-subunit CAPNS1 are ubiquitously found in all tissues. Other calpains likely consist of an isolated L-subunit/chain alone. Many of them, such as CAPNS2, CAPN3 (in skeletal muscle, or lens), CAPN8 (in stomach), CAPN9 (in digestive tracts), CAPN11 (in testis), CAPN12 (in follicles), are tissue-specific and have specific functions in distinct organs. The L-subunits of similar structure (called CALPA and B) also have been found in Drosophila melanogaster. The S-subunit seems to have a chaperone-like function for proper folding of the L-subunit. The catalytic L-subunits contain a short N-terminal anchor helix, followed by a calpain cysteine protease (CysPc) domain, a C2-domain-like (C2L) domain, and a C-terminal Ca2+-binding penta-EF-hand (PEF) domain. The S-subunits only have the PEF domain following an N-terminal Gly-rich hydrophobic domain. The calpains undergo a rearrangement of the protein backbone upon Ca2+-binding.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  73 EPKKEEIKRMISDIDKDCSGRIAFNVFLQLMT-IKmaekdtkeEILKAFRLFDDDDTGKISFRNLKRVARELGETLtDEE 151
Cdd:cd16182   38 GFSLETCRSLIALMDTNGSGRLDLEEFKTLWSdLK--------KWQAIFKKFDTDRSGTLSSYELRKALESAGFHL-SNK 108

                         90       100
                 ....*....|....*....|..
gi 442628888 152 LREMIDEADLDNDGEVNQEEFL 173
Cdd:cd16182  109 VLQALVLRYADSTGRITFEDFV 130

Penta-EF hand, calcium binding motifs, found in Drosophila melanogaster calpain-A (CalpA), calpain-B (CalpB), and similar proteins; The family contains two calpains that have been found in Drosophila, CalpA and CalpB. CalpA, also termed calcium-activated neutral proteinase A (CANP A), or calpain-A catalytic subunit, is a Drosophila calpain homolog specifically expressed in a few neurons in the central nervous system, in scattered endocrine cells in the midgut, and in blood cells. CalpB, also termed calcium-activated neutral proteinase B (CANP B), contains calpain-B catalytic subunit 1 and calpain-B catalytic subunit 2. Both CalpA and CalpB are closely related to that of vertebrate calpains, and they share similar domain architecture, which consists of four domains: the N-terminal domain I, the catalytic domain II carrying the three active site residues, Cys, His and Asn, the Ca2+-regulated phospholipid-binding domain III, and penta-EF-hand Ca2+-binding domain IV. Besides, CalpA and CalpB display some distinguishing structural features that are not found in mammalian typical calpains. CalpA harbors a 76 amino acid long hydrophobic stretch inserted in domain IV, which may be involved in membrane attachment of this enzyme. CalpB has an unusually long N-terminal tail of 224 amino acids, which belongs to the class of intrinsically unstructured proteins (IUP) and may become ordered upon binding to target protein(s). Moreover, they do not need small regulatory subunits for their catalytic activity, and their proteolytic function is not regulated by an intrinsic inhibitor as the Drosophila genome contains neither regulatory subunit nor calpastatin orthologs. As a result, they may exist as a monomer or perhaps as a homo- or heterodimer together with a second large subunit. Furthermore, both CalpA and CalpB are dispensable for viability and fertility and do not share vital functions during Drosophila development. Phosphatidylinositol 4,5-diphosphate, phosphatidylinositol 4-monophosphate, phosphatidylinositol, and phosphatidic acid can stimulate the activity and the rate of activation of CalpA, but not CalpB. Calpain A modulates Toll responses by limited Cactus/IkappaB proteolysis. CalpB directly interacts with talin, an important component of the focal adhesion complex, and functions as an important modulator in border cell migration within egg chambers, which may act via the digestion of talin. CalpB can be phosphorylated by cAMP-dependent protein kinase (protein kinase A, PKA; EC 2.7.11.11) at Ser240 and Ser845, as well as by mitogen-activated protein kinase (ERK1 and ERK2; EC 2.7.11.24) at Thr747. The activation of the ERK pathway by extracellular signals results in the phosphorylation and activation of calpain B. In Schneider cells (S2), calpain B was mainly in the cytoplasm and upon a rise in Ca2+ the enzyme adhered to intracellular membranes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  44 KEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMI---SDIDkdcsGRIAFNVFLQLMT--IKMAEKdtkeeilk 118
Cdd:cd16196   74 KRVFKLFDTDGSGSFSSFELRNALNSAGFRLSNATLNALVlrySNKD----GRISFDDFIMCAVklKTMFEI-------- 141

                         90
                 ....*....|....*
gi 442628888 119 aFRLFDDDDTGKISF 133
Cdd:cd16196  142 -FKEKDPRGGGRATF 155

Penta-EF hand, calcium binding motifs, found in calpain-13 (CAPN13), calpain-14 (CAPN14), and similar proteins; CAPN13, also termed calcium-activated neutral proteinase 13 (CANP 13), a 63.6 kDa calpain large subunit that exhibits a restricted tissue distribution with low levels of expression detected only in human testis and lung. In calpain family, CAPN13 is most closely related to calpain-14 (CAPN14). CAPN14, also termed calcium-activated neutral proteinase 14 (CANP 14), is a 76.7 kDa calpain large subunit that is most highly expressed in the oesophagus. Its expression and calpain activity can be induced by IL-13. Both CAPN13 and CAPN14 contain a calpain cysteine protease (CysPc) domain, a C2-domain-like (C2L) domain, and a C-terminal Ca2+-binding penta-EF-hand (PEF) domain.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  44 KEAFDLFDNEGTGYIEVKELKVAIRALGFePKKEEIKRMISDIDKDCSGRIAFNVFLQLMtIKMaekdtkEEILKAFRLF 123
Cdd:cd16195   76 KDIFQKADVSKSGFLSLSELRNAIQAAGI-RVSDDLLNLMALRYGDSSGRISFESFICLM-LRL------ECMAKIFRNL 147

                         90
                 ....*....|.
gi 442628888 124 DDDDtGKISFR 134
Cdd:cd16195  148 SKDG-GGIYLT 157

EF-hand, calcium binding motif, found in calumenin, reticulocalbin-1 (RCN-1), reticulocalbin-3 (RCN-3), and similar proteins; The family corresponds to a group of six EF-hand Ca2+-binding proteins, including calumenin (also known as crocalbin or CBP-50), reticulocalbin-1 (RCN-1), reticulocalbin-3 (RCN-3), and similar proteins. Calumenin is an endo/sarcoplasmic reticulum (ER/SR) resident low-affinity Ca2+-binding protein that contains six EF-hand domains and a C-terminal SR retention signal His-Asp-Glu-Phe (HDEF) tetrapeptide. It functions as a novel regulator of SERCA2, and its expressional changes are tightly coupled with Ca2+-cycling of cardiomyocytes. It is also broadly involved in haemostasis and in the pathophysiology of thrombosis. Moreover, the extracellular calumenin acts as a suppressor of cell migration and tumor metastasis. RCN-1 is an endoplasmic reticulum resident Ca2+-binding protein with a carboxyl-terminal His-Asp-Glu-Leu (HDEL) tetrapeptide signal. It acts as a potential negative regulator of B-RAF activation and can negatively modulate cardiomyocyte hypertrophy by inhibition of the mitogen-activated protein kinase signalling cascade. It also plays a key role in the development of doxorubicin-associated resistance. RCN-3 is a putative six EF-hand Ca2+-binding protein that contains five RXXR (X is any amino acid) motifs and a C-terminal ER retrieval signal HDEL tetrapeptide. The RXXR motif represents the target sequence of subtilisin-like proprotein convertases (SPCs). RCN-3 is specifically bound to the paired basic amino-acid-cleaving enzyme-4 (PACE4) precursor protein and plays an important role in the biosynthesis of PACE4.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  73 EPKKEEIKRMISDIDKDCSGRIAFNVfLQLMTIKMAEKDTKEEILKAFRLFDDDDTGKISFRNLKRV-----ARELGETL 147
Cdd:cd16226   31 EESKERLGIIVDKIDKNGDGFVTEEE-LKDWIKYVQKKYIREDVDRQWKEYDPNKDGKLSWEEYKKAtygflDDEEEDDD 109

                         90       100       110
                 ....*....|....*....|....*....|..
gi 442628888 148 TDEELREMI-------DEADLDNDGEVNQEEF 172
Cdd:cd16226  110 LHESYKKMIrrderrwKAADQDGDGKLTKEEF 141

Penta-EF hand, calcium binding motifs, found in sorcin, grancalcin, and similar proteins; The family corresponds to the second group of penta-EF hand (PEF) proteins that includes sorcin, grancalcin, and similar proteins. Sorcin, also termed 22 kDa Ca2+-binding protein, CP-22, or V19, is a soluble resistance-related calcium-binding protein that is expressed in normal mammalian tissues, such as the liver, lungs and heart. It contains a flexible glycine and proline-rich N-terminal extension and five EF-hand motifs that associate with membranes in a calcium-dependent manner. It may harbor three potential Ca2+ binding sites through its EF1, EF2 and EF3 hands. However, binding of only two Ca2+/monomer suffices to trigger the conformational change that exposes hydrophobic regions and leads to interaction with the respective targets. Sorcin forms homodimers through the association of the unpaired EF5 hand. Among the PEF proteins, sorcin is unique in that it contains potential phosphorylation sites by cAMP-dependent protein kinase (PKA), and it can form a tetramer at slightly acid pH values although remaining a stable dimer at neutral pH. Grancalcin (GCA) is a cytosolic Ca2+-binding protein specifically expressed in neutrophils and monocytes/macrophages. It can strongly interact with sorcin to form a heterodimer and further modulate the function of sorcin. GCA exists as homodimers in solution. It contains five EF-hand motifs attached to an N-terminal region of an approximately 50 residue-long segment rich in glycines and prolines. In contrast with sorcin, GCA binds two Ca2+ ions through its EF1 and EF3 hands.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  44 KEAFDLFDNEGTGYIEVKELKVAIRALGFEPKKEEIKRMISDIDKDcsGRIAFNVFLQLMTIKMAEKDtkeeilkAFRLF 123
Cdd:cd16181   73 KTTFMQYDRDRSGTVEPQELQQAIRSFGYNLSPQALNVIVKRYSKN--GRITFDDFVACAVRLRALTD-------RFRRR 143

                         90
                 ....*....|.
gi 442628888 124 DDDDTGKISFR 134
Cdd:cd16181  144 DTQQNGTATFQ 154

EF-hand, calcium binding motif, found in apoptosis-linked gene 2 protein (ALG-2) and similar proteins; ALG-2, also termed programmed cell death protein 6 (PDCD6), or probable calcium-binding protein ALG-2, is one of the prototypic members of the penta EF-hand protein family. It is a widely expressed calcium-binding modulator protein associated with cell proliferation and death, as well as cell survival. ALG-2 acts as a pro-apoptotic factor participating in T cell receptor-, Fas-, and glucocorticoid-induced programmed cell death, and also serves as a useful molecular marker for the prognosis of cancers. Moreover, ALG-2 functions as a calcium ion sensor at endoplasmic reticulum (ER) exit sites, and modulates ER-stress-stimulated cell death and neuronal apoptosis during organ formation. Furthermore, ALG-2 can mediate the pro-apoptotic activity of cisplatin or tumor necrosis factor alpha (TNFalpha) through the down-regulation of nuclear factor-kappaB (NF-kappaB) expression. It also inhibits angiogenesis through PI3K/mTOR/p70S6K pathway by interacting of vascular endothelial growth factor receptor-2 (VEGFR-2). In addition, nuclear ALG-2 may participate in the post-transcriptional regulation of Inositol Trisphosphate Receptor Type 1 (IP3R1) pre-mRNA at least in part by interacting with CHERP (Ca2+ homeostasis endoplasmic reticulum protein) calcium-dependently. ALG-2 contains five serially repeated EF-hand motifs and interacts with various proteins, including ALG-2-interacting protein X (Alix), Fas, annexin XI, death-associated protein kinase 1 (DAPk1), Tumor susceptibility gene 101 (TSG101), Sec31A, phospholipid scramblase 3 (PLSCR3), the P-body component PATL1, and endosomal sorting complex required for transport (ESCRT)-III-related protein IST1, in a calcium-dependent manner. It forms a homodimer in the cell or a heterodimer with its closest paralog peflin. Among the PEF proteins, ALG-2 can bind three Ca2+ ions through its EF1, EF3, and EF5 hands, where it is unique in that its EF5 hand binds Ca2+ ion in a canonical coordination.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  51 DNEGTGYIEVKELKVAIRALGFEPKKEEIKR-MISDIDKDCSGRIAFNVFLQLMtikmaekdtK--EEILKAFRLFDDDD 127
Cdd:cd16183   10 DKDRSGQISATELQQALSNGTWTPFNPETVRlMIGMFDRDNSGTINFQEFAALW---------KyiTDWQNCFRSFDRDN 80

                         90       100
                 ....*....|....*....|...
gi 442628888 128 TGKISFRNLKRVARELGETLTDE 150
Cdd:cd16183   81 SGNIDKNELKQALTSFGYRLSDQ 103

EF-hand, calcium binding motif, found in alpha-parvalbumin; Alpha-parvalbumin is cytosolic Ca2+/Mg2+-binding protein expressed mainly in fast-twitch skeletal myofibrils, where it may act as a soluble relaxing factor facilitating the Ca2+-mediated relaxation phase. It is also expressed in rapidly firing neurons, particularly GABA-ergic neurons, and thus may confer protection against Ca2+ toxicity. The major role of alpha-parvalbumin is metal buffering and transport of Ca2+. It binds different metal cations, and exhibits very high affinity for Ca2+ and physiologically significant affinity for Mg2+. Alpha-parvalbumin is characterized by the presence of three consecutive EF-hand motifs (helix-loop-helix) called AB, CD, and EF, but only CD and EF can chelate metal ions, such as Ca2+ and Mg2+. Both metal ion-binding sites in alpha-parvalbumin are high-affinity sites. Additionally, in contrast to beta-parvalbumin, alpha-parvalbumin is less acidic and has an additional residue in the C-terminal helix.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 442628888  77 EEIKRMISDIDKdcSGRIAFNVFLQLMTIKmaeKDTKEEILKAFRLFDDDDTGKISFRNLKRVAREL---GETLTDEELR 153
Cdd:cd16254    2 EDIKKAVGAFAA--ADSFDYKKFFEMVGLK---KKSADDVKKVFHILDKDKSGFIEEDELKFVLKGFspdGRDLSDKETK 76

                         90
                 ....*....|....*....
gi 442628888 154 EMIDEADLDNDGEVNQEEF 172
Cdd:cd16254   77 ALLAAGDKDGDGKIGIDEF 95