Src homology 2 (SH2) domain found in B-cell linker (BLNK) protein and SH2 domain-containing leukocyte protein of 76 kDa (SLP-76); BLNK (also known as SLP-65 or BASH) is an important adaptor protein expressed in B-lineage cells. BLNK consists of a N-terminal sterile alpha motif (SAM) domain and a C-terminal SH2 domain. BLNK is a cytoplasmic protein, but a part of it is bound to the plasma membrane through an N-terminal leucine zipper motif and transiently bound to a cytoplasmic domain of Iga through its C-terminal SH2 domain upon B cell antigen receptor (BCR)-stimulation. A non-ITAM phosphotyrosine in Iga is necessary for the binding with the BLNK SH2 domain and/or for normal BLNK function in signaling and B cell activation. Upon phosphorylation BLNK binds Btk and PLCgamma2 through their SH2 domains and mediates PLCgamma2 activation by Btk. BLNK also binds other signaling molecules such as Vav, Grb2, Syk, and HPK1. BLNK has been shown to be necessary for BCR-mediated Ca2+ mobilization, for the activation of mitogen-activated protein kinases such as ERK, JNK, and p38 in a chicken B cell line DT40, and for activation of transcription factors such as NF-AT and NF-kappaB in human or mouse B cells. BLNK is involved in B cell development, B cell survival, activation, proliferation, and T-independent immune responses. BLNK is structurally homologous to SLP-76. SLP-76 and (linker for activation of T cells) LAT are adaptor/linker proteins in T cell antigen receptor activation and T cell development. BLNK interacts with many downstream signaling proteins that interact directly with both SLP-76 and LAT. New data suggest functional complementation of SLP-76 and LAT in T cell antigen receptor function with BLNK in BCR function. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 213 SAAEDSDLLTQPWYSGNCDRYAVESALLHLQKDGAYTVRPSSGPHGSQPFTLAVLLRGRVFNIPIRRLDGGRHYALGREG 292
Cdd:cd09929     1 SAEEEADLLPKEWYAGNIDRKEAEEALRRSNKDGTFLVRDSSGKDSSQPYTLMVLYNDKVYNIQIRFLENTRQYALGTGL 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|..
gi 2028574122 293 RnREELFSSVAAMVQHFMWHPLPLVDRHSGSRELTCLLFPTK 334
Cdd:cd09929    81 R-GEETFSSVAEIIEHHQKTPLLLIDGKDNTKDSTCLLYAAG 121

Src homology 2 (SH2) domain found in B-cell linker (BLNK) protein and SH2 domain-containing leukocyte protein of 76 kDa (SLP-76); BLNK (also known as SLP-65 or BASH) is an important adaptor protein expressed in B-lineage cells. BLNK consists of a N-terminal sterile alpha motif (SAM) domain and a C-terminal SH2 domain. BLNK is a cytoplasmic protein, but a part of it is bound to the plasma membrane through an N-terminal leucine zipper motif and transiently bound to a cytoplasmic domain of Iga through its C-terminal SH2 domain upon B cell antigen receptor (BCR)-stimulation. A non-ITAM phosphotyrosine in Iga is necessary for the binding with the BLNK SH2 domain and/or for normal BLNK function in signaling and B cell activation. Upon phosphorylation BLNK binds Btk and PLCgamma2 through their SH2 domains and mediates PLCgamma2 activation by Btk. BLNK also binds other signaling molecules such as Vav, Grb2, Syk, and HPK1. BLNK has been shown to be necessary for BCR-mediated Ca2+ mobilization, for the activation of mitogen-activated protein kinases such as ERK, JNK, and p38 in a chicken B cell line DT40, and for activation of transcription factors such as NF-AT and NF-kappaB in human or mouse B cells. BLNK is involved in B cell development, B cell survival, activation, proliferation, and T-independent immune responses. BLNK is structurally homologous to SLP-76. SLP-76 and (linker for activation of T cells) LAT are adaptor/linker proteins in T cell antigen receptor activation and T cell development. BLNK interacts with many downstream signaling proteins that interact directly with both SLP-76 and LAT. New data suggest functional complementation of SLP-76 and LAT in T cell antigen receptor function with BLNK in BCR function. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 213 SAAEDSDLLTQPWYSGNCDRYAVESALLHLQKDGAYTVRPSSGPHGSQPFTLAVLLRGRVFNIPIRRLDGGRHYALGREG 292
Cdd:cd09929     1 SAEEEADLLPKEWYAGNIDRKEAEEALRRSNKDGTFLVRDSSGKDSSQPYTLMVLYNDKVYNIQIRFLENTRQYALGTGL 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|..
gi 2028574122 293 RnREELFSSVAAMVQHFMWHPLPLVDRHSGSRELTCLLFPTK 334
Cdd:cd09929    81 R-GEETFSSVAEIIEHHQKTPLLLIDGKDNTKDSTCLLYAAG 121

N-terminal domain of transcription factor Specificity Protein (SP) 2; Specificity Proteins (SPs) are transcription factors that are involved in many cellular processes, including cell differentiation, cell growth, apoptosis, immune responses, response to DNA damage, and chromatin remodeling. SP2 contains the least conserved DNA-binding domain within the SP subfamily of proteins, and its DNA sequence specificity differs from the other SP proteins. It localizes primarily within subnuclear foci associated with the nuclear matrix, and can activate, or in some cases, repress expression from different promoters. The transcription factor SP2 serves as a paradigm for indirect genomic binding. It does not require its DNA-binding domain for genomic DNA binding and occupies target promoters independently of whether they contain a cognate DNA-binding motif. SP2 belongs to a family of proteins, called the SP/Kruppel or Krueppel-like Factor (KLF) family, characterized by a C-terminal DNA-binding domain of 81 amino acids consisting of three Kruppel-like C2H2 zinc fingers. These factors bind to a loose consensus motif, namely NNRCRCCYY (where N is any nucleotide; R is A/G, and Y is C/T), such as the recurring motifs in GC and GT boxes (5'-GGGGCGGGG-3' and 5-GGTGTGGGG-3') that are present in promoters and more distal regulatory elements of mammalian genes. SP factors preferentially bind GC boxes, while KLFs bind CACCC boxes. Another characteristic hallmark of SP factors is the presence of the Buttonhead (BTD) box CXCPXC, just N-terminal to the zinc fingers. The function of the BTD box is unknown, but it is thought to play an important physiological role. Another feature of most SP factors is the presence of a conserved amino acid stretch, the so-called SP box, located close to the N-terminus. SP factors may be separated into three groups based on their domain architecture and the similarity of their N-terminal transactivation domains: SP1-4, SP5, and SP6-9. The transactivation domains between the three groups are not homologous to one another. SP1-4 have similar N-terminal transactivation domains characterized by glutamine-rich regions, which, in most cases, have adjacent serine/threonine-rich regions. This model represents the N-terminal domain of SP2.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122  91 PSKPSPPLPQPTML------KGAVSLPvagkQGPIFGRREQGASSRVVPGPPKKPDEDLYLECEPDPVLALTQTLSFQ-V 163
Cdd:cd22540   278 PGTGQPAVLQQVQVlqpkqeQQVVQIP----QQALRVVQAASATLPTVPQKPLQNIQIQNSEPTPTQVYIKTPSGEVQtV 353

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 2028574122 164 LMPSGPlprTSVVPRPTTAPQETRNGTADAASKEGRKSS-------LPSVAPTGS 211
Cdd:cd22540   354 LLQEAP---AATATPSSSTSTVQQQVTANNGTGTSKPNYnvrkertLPKIAPAGG 405

Src homology 2 (SH2) domain found in B-cell linker (BLNK) protein and SH2 domain-containing leukocyte protein of 76 kDa (SLP-76); BLNK (also known as SLP-65 or BASH) is an important adaptor protein expressed in B-lineage cells. BLNK consists of a N-terminal sterile alpha motif (SAM) domain and a C-terminal SH2 domain. BLNK is a cytoplasmic protein, but a part of it is bound to the plasma membrane through an N-terminal leucine zipper motif and transiently bound to a cytoplasmic domain of Iga through its C-terminal SH2 domain upon B cell antigen receptor (BCR)-stimulation. A non-ITAM phosphotyrosine in Iga is necessary for the binding with the BLNK SH2 domain and/or for normal BLNK function in signaling and B cell activation. Upon phosphorylation BLNK binds Btk and PLCgamma2 through their SH2 domains and mediates PLCgamma2 activation by Btk. BLNK also binds other signaling molecules such as Vav, Grb2, Syk, and HPK1. BLNK has been shown to be necessary for BCR-mediated Ca2+ mobilization, for the activation of mitogen-activated protein kinases such as ERK, JNK, and p38 in a chicken B cell line DT40, and for activation of transcription factors such as NF-AT and NF-kappaB in human or mouse B cells. BLNK is involved in B cell development, B cell survival, activation, proliferation, and T-independent immune responses. BLNK is structurally homologous to SLP-76. SLP-76 and (linker for activation of T cells) LAT are adaptor/linker proteins in T cell antigen receptor activation and T cell development. BLNK interacts with many downstream signaling proteins that interact directly with both SLP-76 and LAT. New data suggest functional complementation of SLP-76 and LAT in T cell antigen receptor function with BLNK in BCR function. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 213 SAAEDSDLLTQPWYSGNCDRYAVESALLHLQKDGAYTVRPSSGPHGSQPFTLAVLLRGRVFNIPIRRLDGGRHYALGREG 292
Cdd:cd09929     1 SAEEEADLLPKEWYAGNIDRKEAEEALRRSNKDGTFLVRDSSGKDSSQPYTLMVLYNDKVYNIQIRFLENTRQYALGTGL 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|..
gi 2028574122 293 RnREELFSSVAAMVQHFMWHPLPLVDRHSGSRELTCLLFPTK 334
Cdd:cd09929    81 R-GEETFSSVAEIIEHHQKTPLLLIDGKDNTKDSTCLLYAAG 121

Src homology 2 (SH2) domain; In general, SH2 domains are involved in signal transduction; they bind pTyr-containing polypeptide ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites. They are present in a wide array of proteins including: adaptor proteins (Nck1, Crk, Grb2), scaffolds (Slp76, Shc, Dapp1), kinases (Src, Syk, Fps, Tec), phosphatases (Shp-1, Shp-2), transcription factors (STAT1), Ras signaling molecules (Ras-Gap), ubiquitination factors (c-Cbl), cytoskeleton regulators (Tensin), signal regulators (SAP), and phospholipid second messengers (PLCgamma), amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 224 PWYSGNCDRYAVEsALLHLQKDGAYTVRPSSGPHGSqpFTLAVLLR-GRVFNIPIRRLDGGRHYALGREGRnreelFSSV 302
Cdd:cd00173     1 PWFHGSISREEAE-RLLRGKPDGTFLVRESSSEPGD--YVLSVRSGdGKVKHYLIERNEGGYYLLGGSGRT-----FPSL 72

                  ....*..
gi 2028574122 303 AAMVQHF 309
Cdd:cd00173    73 PELVEHY 79

Src homology 2 domain found in SH2 domain-containing adapter proteins B, D, E, and F (SHB, SHD, SHE, SHF); SHB, SHD, SHE, and SHF are SH2 domain-containing proteins that play various roles throughout the cell. SHB functions in generating signaling compounds in response to tyrosine kinase activation. SHB contains proline-rich motifs, a phosphotyrosine binding (PTB) domain, tyrosine phosphorylation sites, and a SH2 domain. SHB mediates certain aspects of platelet-derived growth factor (PDGF) receptor-, fibroblast growth factor (FGF) receptor-, neural growth factor (NGF) receptor TRKA-, T cell receptor-, interleukin-2 (IL-2) receptor- and focal adhesion kinase- (FAK) signaling. SRC-like FYN-Related Kinase FRK/RAK (also named BSK/IYK or GTK) and SHB regulate apoptosis, proliferation and differentiation. SHB promotes apoptosis and is also required for proper mitogenicity, spreading and tubular morphogenesis in endothelial cells. SHB also plays a role in preventing early cavitation of embryoid bodies and reduces differentiation to cells expressing albumin, amylase, insulin and glucagon. SHB is a multifunctional protein that has difference responses in different cells under various conditions. SHE is expressed in heart, lung, brain, and skeletal muscle, while expression of SHD is restricted to the brain. SHF is mainly expressed in skeletal muscle, brain, liver, prostate, testis, ovary, small intestine, and colon. SHD may be a physiological substrate of c-Abl and may function as an adapter protein in the central nervous system. It is also thought to be involved in apoptotic regulation. SHD contains five YXXP motifs, a substrate sequence preferred by Abl tyrosine kinases, in addition to a poly-proline rich region and a C-terminal SH2 domain. SHE contains two pTry protein binding domains, protein interaction domain (PID) and a SH2 domain, followed by a glycine-proline rich region, all of which are N-terminal to the phosphotyrosine binding (PTB) domain. SHF contains four putative tyrosine phosphorylation sites and an SH2 domain. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 223 QPWYSGNCDRYAVESaLLHLQKDGAYTVRPSSGphGSQPFTLAVLLRGRVFNIPIRRLDGGRhYALGREGRnreeLFSSV 302
Cdd:cd09945     1 QGWYHGAITRIEAES-LLRPCKEGSYLVRNSES--TKQDYSLSLKSAKGFMHMRIQRNETGQ-YILGQFSR----PFETI 72

                          90       100       110
                  ....*....|....*....|....*....|
gi 2028574122 303 AAMVQHFMWHPLPLvdrhSGSRELtCLLFP 332
Cdd:cd09945    73 PEMIRHYCLNKLPV----RGAEHM-CLLEP 97

Src homology 2 (SH2) domain found in feline sarcoma, Fujinami poultry sarcoma, and fes-related (Fes/Fps/Fer) proteins; The Fps family consists of members Fps/Fes and Fer/Flk/Tyk3. They are cytoplasmic protein-tyrosine kinases implicated in signaling downstream from cytokines, growth factors and immune receptors. Fes/Fps/Fer contains three coiled-coil regions, an SH2 (Src-homology-2) and a TK (tyrosine kinase catalytic) domain signature. Members here include: Fps/Fes, Fer, Kin-31, and In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 219 DLLTQPWYSGNCDRYAVEsALLHlqKDGAYTVRPSSGPHGSQP-FTLAVLLRGRVFNIPIRRLDGGRHYalgregrNREE 297
Cdd:cd10361     2 DLENEPYYHGLLPREDAE-ELLK--NDGDFLVRKTEPKGGGKRkLVLSVRWDGKIRHFVINRDDGGKYY-------IEGK 71

                          90
                  ....*....|....*....
gi 2028574122 298 LFSSVAAMVQHFMWHPLPL 316
Cdd:cd10361    72 SFKSISELINYYQKTKEPI 90

Src homology 2 (SH2) domain found in the Src oncogene at 42A (Src42); Src42 is a member of the Src non-receptor type tyrosine kinase family of proteins. The integration of receptor tyrosine kinase-induced RAS and Src42 signals by Connector eNhancer of KSR (CNK) as a two-component input is essential for RAF activation in Drosophila. Src42 is present in a wide variety of organisms including: California sea hare, pea aphid, yellow fever mosquito, honey bee, Panamanian leafcutter ant, and sea urchin. Src42 has a unique N-terminal domain, an SH3 domain, an SH2 domain, a kinase domain and a regulatory tail, as do the other members of the family. Like the other members of the Src family the SH2 domain in addition to binding the target, also plays an autoinhibitory role by binding to its C-terminal tail. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 222 TQPWYSGNCDRYAVESALLHLQKD-GAYTVRPSSGPHGSqpFTLAVLLRGRVFNIPIRRLDGGRHYALgregrnREELFS 300
Cdd:cd10370     2 AEPWYFGKIKRIEAEKKLLLPENEhGAFLIRDSESRHND--YSLSVRDGDTVKHYRIRQLDEGGFFIA------RRTTFR 73

                  ....*....
gi 2028574122 301 SVAAMVQHF 309
Cdd:cd10370    74 TLQELVEHY 82

Src homology 2 (SH2) domain found in the Fyn-related kinase (Frk); Frk is a member of the Src non-receptor type tyrosine kinase family of proteins. The Frk subfamily is composed of Frk/Rak and Iyk/Bsk/Gst. It is expressed primarily epithelial cells. Frk is a nuclear protein and may function during G1 and S phase of the cell cycle and suppress growth. Unlike the other Src members it lacks a glycine at position 2 of SH4 which is important for addition of a myristic acid moiety that is involved in targeting Src PTKs to cellular membranes. FRK and SHB exert similar effects when overexpressed in rat phaeochromocytoma (PC12) and beta-cells, where both induce PC12 cell differentiation and beta-cell proliferation. Under conditions that cause beta-cell degeneration these proteins augment beta-cell apoptosis. The FRK-SHB responses involve FAK and insulin receptor substrates (IRS) -1 and -2. Frk has been demonstrated to interact with retinoblastoma protein. Frk regulates PTEN protein stability by phosphorylating PTEN, which in turn prevents PTEN degradation. Frk also plays a role in regulation of embryonal pancreatic beta cell formation. Frk has a unique N-terminal domain, an SH3 domain, an SH2 domain, a kinase domain and a regulatory tail, as do the other members of the family. Like the other members of the Src family the SH2 domain in addition to binding the target, also plays an autoinhibitory role by binding to its activation loop. The tryosine involved is at the same site as the tyrosine involved in the autophosphorylation of Src. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 223 QPWYSGNCDRYAVESALLHLQ-KDGAYTVRPSSGPHGSqpFTLAVLLRGRVFNIPIRRLDGGRHYAlgregrNREELFSS 301
Cdd:cd10369     3 EPWFFGAIKRADAEKQLLYSEnQTGAFLIRESESQKGE--FSLSVLDGGVVKHYRIRRLDEGGFFL------TRRKTFST 74

                  ....*...
gi 2028574122 302 VAAMVQHF 309
Cdd:cd10369    75 LNEFVNYY 82

Src homology 2 (SH2) domain found in the Vav family; Vav proteins are involved in several processes that require cytoskeletal reorganization, such as the formation of the immunological synapse (IS), phagocytosis, platelet aggregation, spreading, and transformation. Vavs function as guanine nucleotide exchange factors (GEFs) for the Rho/Rac family of GTPases. Vav family members have several conserved motifs/domains including: a leucine-rich region, a leucine-zipper, a calponin homology (CH) domain, an acidic domain, a Dbl-homology (DH) domain, a pleckstrin homology (PH) domain, a cysteine-rich domain, 2 SH3 domains, a proline-rich region, and a SH2 domain. Vavs are the only known Rho GEFs that have both the DH/PH motifs and SH2/SH3 domains in the same protein. The leucine-rich helix-loop-helix (HLH) domain is thought to be involved in protein heterodimerization with other HLH proteins and it may function as a negative regulator by forming inactive heterodimers. The CH domain is usually involved in the association with filamentous actin, but in Vav it controls NFAT stimulation, Ca2+ mobilization, and its transforming activity. Acidic domains are involved in protein-protein interactions and contain regulatory tyrosines. The DH domain is a GDP-GTP exchange factor on Rho/Rac GTPases. The PH domain in involved in interactions with GTP-binding proteins, lipids and/or phosphorylated serine/threonine residues. The SH3 domain is involved in localization of proteins to specific sites within the cell interacting with protein with proline-rich sequences. The SH2 domain mediates a high affinity interaction with tyrosine phosphorylated proteins. There are three Vav mammalian family members: Vav1 which is expressed in the hematopoietic system, Vav2 and Vav3 are more ubiquitously expressed. The members here include insect and amphibian Vavs. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 219 DLLTQPWYSGNCDRYAVESaLLHLQKDGAYTVRPSsgPHGSQPFTLAVLLRGRVFNIPIRRLDGGRHYAlgREGRnreeL 298
Cdd:cd09940     1 DLSEFLWFVGEMERDTAEN-RLENRPDGTYLVRVR--PQGETQYALSIKYNGDVKHMKIEQRSDGLYYL--SESR----H 71

                          90
                  ....*....|....*.
gi 2028574122 299 FSSVAAMVQHFMWHPL 314
Cdd:cd09940    72 FKSLVELVNYYERNSL 87

N-terminal domain of transcription factor Specificity Protein (SP) 2; Specificity Proteins (SPs) are transcription factors that are involved in many cellular processes, including cell differentiation, cell growth, apoptosis, immune responses, response to DNA damage, and chromatin remodeling. SP2 contains the least conserved DNA-binding domain within the SP subfamily of proteins, and its DNA sequence specificity differs from the other SP proteins. It localizes primarily within subnuclear foci associated with the nuclear matrix, and can activate, or in some cases, repress expression from different promoters. The transcription factor SP2 serves as a paradigm for indirect genomic binding. It does not require its DNA-binding domain for genomic DNA binding and occupies target promoters independently of whether they contain a cognate DNA-binding motif. SP2 belongs to a family of proteins, called the SP/Kruppel or Krueppel-like Factor (KLF) family, characterized by a C-terminal DNA-binding domain of 81 amino acids consisting of three Kruppel-like C2H2 zinc fingers. These factors bind to a loose consensus motif, namely NNRCRCCYY (where N is any nucleotide; R is A/G, and Y is C/T), such as the recurring motifs in GC and GT boxes (5'-GGGGCGGGG-3' and 5-GGTGTGGGG-3') that are present in promoters and more distal regulatory elements of mammalian genes. SP factors preferentially bind GC boxes, while KLFs bind CACCC boxes. Another characteristic hallmark of SP factors is the presence of the Buttonhead (BTD) box CXCPXC, just N-terminal to the zinc fingers. The function of the BTD box is unknown, but it is thought to play an important physiological role. Another feature of most SP factors is the presence of a conserved amino acid stretch, the so-called SP box, located close to the N-terminus. SP factors may be separated into three groups based on their domain architecture and the similarity of their N-terminal transactivation domains: SP1-4, SP5, and SP6-9. The transactivation domains between the three groups are not homologous to one another. SP1-4 have similar N-terminal transactivation domains characterized by glutamine-rich regions, which, in most cases, have adjacent serine/threonine-rich regions. This model represents the N-terminal domain of SP2.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122  91 PSKPSPPLPQPTML------KGAVSLPvagkQGPIFGRREQGASSRVVPGPPKKPDEDLYLECEPDPVLALTQTLSFQ-V 163
Cdd:cd22540   278 PGTGQPAVLQQVQVlqpkqeQQVVQIP----QQALRVVQAASATLPTVPQKPLQNIQIQNSEPTPTQVYIKTPSGEVQtV 353

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 2028574122 164 LMPSGPlprTSVVPRPTTAPQETRNGTADAASKEGRKSS-------LPSVAPTGS 211
Cdd:cd22540   354 LLQEAP---AATATPSSSTSTVQQQVTANNGTGTSKPNYnvrkertLPKIAPAGG 405

Src homology 2 (SH2) domain in the Breast Cancer Anti-estrogen Resistance protein 3; BCAR3 is part of a growing family of guanine nucleotide exchange factors is responsible for activation of Ras-family GTPases, including Sos1 and 2, GRF1 and 2, CalDAG-GEF/GRP1-4, C3G, cAMP-GEF/Epac 1 and 2, PDZ-GEFs, MR-GEF, RalGDS family members, RalGPS, RasGEF, Smg GDS, and phospholipase C(epsilon). 12102558 21262352 BCAR3 binds to the carboxy-terminus of BCAR1/p130Cas, a focal adhesion adapter protein. Over expression of BCAR1 (p130Cas) and BCAR3 induces estrogen independent growth in normally estrogen-dependent cell lines. They have been linked to resistance to anti-estrogens in breast cancer, Rac activation, and cell motility, though the BCAR3/p130Cas complex is not required for this activity in BCAR3. Many BCAR3-mediated signaling events in epithelial and mesenchymal cells are independent of p130Cas association. Structurally these proteins contain a single SH2 domain upstream of their RasGEF domain, which is responsible for the ability of BCAR3 to enhance p130Cas over-expression-induced migration. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 2028574122 218 SDLLTQPWYSGNCDRYAVESALlhlQKDGAYTVRPSsgphGSQP--FTLAVLLRGRVFNIPIRRLdggrhyALG-REGRN 294
Cdd:cd10337     1 EDLRSHAWYHGRIPRQVAESLV---QREGDFLVRDS----LSSPgdYVLTCRWKGQPLHFKINRV------VLRpSEAYT 67

                          90       100
                  ....*....|....*....|....*...
gi 2028574122 295 R------EELFSSVAAMVQHFMWHPLPL 316
Cdd:cd10337    68 RvqyqfeDEQFDSIPALVHFYVGNRRPI 95

Src homology 2 (SH2) domain found in Tec-like proteins; The Tec protein tyrosine kinase is the founding member of a family that includes Btk, Itk, Bmx, and Txk. The members have a PH domain, a zinc-binding motif, a SH3 domain, a SH2 domain, and a protein kinase catalytic domain. Btk is involved in B-cell receptor signaling with mutations in Btk responsible for X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (xid) in mice. Itk is involved in T-cell receptor signaling. Tec is expressed in both T and B cells, and is thought to function in activated and effector T lymphocytes to induce the expression of genes regulated by NFAT transcription factors. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30
                  ....*....|....*....|....*....|..
gi 2028574122 225 WYSGNCDRYAVESALLHLQKDGAYTVRPSSGP 256
Cdd:cd09934     8 WYVGDMSRQRAESLLKQEDKEGCFVVRNSSTK 39