Cyclin box fold superfamily; The cyclin box is a protein binding domain that functions in cell-cycle and transcriptional control. It is about 100 amino acids in length, composed of five helices, and is present in cyclins, transcription initiation factor IIB (TFIIB), and retinoblastoma tumour suppressor protein (Rb). Cyclins consist of 8 classes of cell cycle regulators that function as regulatory subunits of cyclin-dependent kinases (CDKs), which are serine/threonine kinases. The catalytic activities of CDKs are modulated not only by their interactions with cyclins but also by CDK inhibitors (CKIs). CDKs, cyclins and CKIs play key roles in transcription, epigenetic regulation, metabolism, stem cell self-renewal, neuronal functions, and spermatogenesis. TFIIB is a transcription factor that binds the TATA box. Members in this superfamily contain one or two copies of the cyclin box.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20575    65 EVCEEQKCEEEVFPLAMNYVDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDNSISPRQLLDWEILVL 144

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20575   145 GKLKWD 150

first cyclin box found in G1/S-specific cyclin-D3 (CCND3) and similar proteins; CCND3 is a regulatory component of the cyclin D3-CDK4 (DC) complex that phosphorylates and inhibits members of the retinoblastoma (RB) protein family, including RB1, and regulates the cell-cycle during G(1)/S transition. In skeletal muscle, CCND3 plays a unique function in controlling the proliferation/differentiation balance of myogenic progenitor cells. CCND3 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20575    65 EVCEEQKCEEEVFPLAMNYVDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDNSISPRQLLDWEILVL 144

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20575   145 GKLKWD 150

Cyclin, C-terminal domain; Cyclins regulate cyclin dependent kinases (CDKs). Swiss:P22674 is a Uracil-DNA glycosylase that is related to other cyclins. Cyclins contain two domains of similar all-alpha fold, of which this family corresponds with the C-terminal domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 219 VIAHDFLALILHRLSLPRDRQalVKKHAQTFLALCATDYTFAMYPPSMIATGSIGAAVQGLGacsmsGDELTELLAGITG 298
Cdd:pfam02984   1 PTPLSFLRRFSKAADYLHDLE--LRTLAKYLLELTLLDYDFLKYPPSLIAAAAVYLARKTLN-----SPEWTETLEHYTG 73

                          90
                  ....*....|....*..
gi 1751273124 299 TEVDCLRACQEQIEAAL 315
Cdd:pfam02984  74 YSEEDLKPCVKLLLELL 90

Cyclin [Cell division and chromosome partitioning];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 140 EVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVLGKLKWDLAAV 219
Cdd:COG5024   232 ETLFLAINIIDRFLSSRVVSLEKYQLVGISALFIASKYEEVNCPSIKDLVYATDGAFTRDDIIRAERYMLEVLDFNISWP 311

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 220 IAHDFlaliLHRLSLPRDRQALVKKHAQTFLALCATDYTFAMYPPSMIAtgsigAAVQGLGACSMSGDELTELLAGITG- 298
Cdd:COG5024   312 SPMSF----LRRISKASDYDIFSRTPAKFSSEISPVDYKFIQISPSWCA-----AAAMYLSRKILSQNQWDRTLIHYSGn 382

                         170       180       190
                  ....*....|....*....|....*....|....*..
gi 1751273124 299 -TEVDCLRACQEqieaaLRESLREAAQTSSSPAPKAP 334
Cdd:COG5024   383 yTNPDLKPLNES-----NKENLQNPSVHHDAIFPKYP 414

first cyclin box found in G1/S-specific cyclin-D3 (CCND3) and similar proteins; CCND3 is a regulatory component of the cyclin D3-CDK4 (DC) complex that phosphorylates and inhibits members of the retinoblastoma (RB) protein family, including RB1, and regulates the cell-cycle during G(1)/S transition. In skeletal muscle, CCND3 plays a unique function in controlling the proliferation/differentiation balance of myogenic progenitor cells. CCND3 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20575    65 EVCEEQKCEEEVFPLAMNYVDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDNSISPRQLLDWEILVL 144

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20575   145 GKLKWD 150

first cyclin box found in G1/S-specific cyclin-D2 (CCND2); CCND2 is a regulatory component of the cyclin D2-CDK4 (DC) complex that phosphorylates and inhibits members of the retinoblastoma (RB) protein family, including RB1, and regulates the cell-cycle during G(1)/S transition. It is a critical mediator of exercise-induced cardiac hypertrophy. It also acts as a regulator of cell cycle proteins affecting SAMHD1-mediated HIV-1 restriction in non-proliferating macrophages. CCND2 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20574    65 EVCEEQKCEEEVFPLAMNYLDRFLAVVPTRKCHLQLLGAVCMFLASKLKETIPLTAEKLCIYTDNSIKPQELLEWELVVL 144

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20574   145 GKLKWN 150

first cyclin box found in G1/S-specific cyclin-D1 (CCND1); CCND1, also called B-cell lymphoma 1 protein (BCL-1), or BCL-1 oncogene, or PRAD1 oncogene, is a regulatory component of the cyclin D1-CDK4 (DC) complex that phosphorylates and inhibits members of the retinoblastoma (RB) protein family, including RB1. The complex also regulates the cell-cycle during G(1)/S transition. It is an important cell cycle regulatory protein involved in carcinogenesis of various human cancers. CCND1 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20573    64 EVCEEQKCEEEVFPLAMNYLDRFLSVEPTKKSRLQLLGATCMFLASKMKETIPLTAEKLCIYTDNSIRPEELLQMELLVL 143

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20573   144 NKLKWD 149

Cyclin, N-terminal domain; Cyclins regulate cyclin dependent kinases (CDKs). Swiss:P22674 is a Uracil-DNA glycosylase that is related to other cyclins. Cyclins contain two domains of similar all-alpha fold, of which this family corresponds with the N-terminal domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:pfam00134  40 EVHEKFKLLPETLYLAVNYLDRFLSKKSVPKNKLQLVGVTCLFIAAKYEEIYPPTVEDLVYITDNAYTREEILRMERLIL 119

                  ....*...
gi 1751273124 210 GKLKWDLA 217
Cdd:pfam00134 120 ETLNFDLS 127

first cyclin box found in cyclin-A (CCNA) family; The CCNA family includes two A-type cyclins, CCNA1 and CCNA2. CCNA1 may primarily function in the control of the germline meiotic cell cycle and additionally in the control of mitotic cell cycle in some somatic cells. CCNA2 controls both the G1/S and the G2/M transition phases of the cell cycle. Members in this family contain two cyclin boxes. The model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20504    44 EVAEEYKLVPETLYLAVNYIDRFLSQMSVLRSKLQLVGTACMFIAAKYEEIYPPEVEEFVYITDDTYTKKQVLRMEHLVL 123

                  ....
gi 1751273124 210 GKLK 213
Cdd:cd20504   124 KVLS 127

cyclin box found in Cyclin N-terminal domain-containing protein 2 (CNTD2) and similar proteins; CNTD2 is an atypical cyclin upregulated in human cancer tissues. It promotes cell proliferation and migration, as well as increases tumor growth in vivo. It can function as a prognostic factor and drug target. CNTD2 contains one cyclin box. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20542    10 QVQEHLELSTQTLHLAVALLDRYLSRQKISLSLLQLLGITCLFIACKFEERFPPEVATLCYLTDDSYSKKQVLRMERRVL 89

                  ....*..
gi 1751273124 210 GKLKWDL 216
Cdd:cd20542    90 RRLRFDL 96

first cyclin box found in viral cyclin (v-cyclin); v-Cyclin modulates host cell cycle progression and apoptotic signaling pathways. It forms an active kinase complex with cellular CDK6, a cellular cyclin-dependent kinase known to interact with cellular type D cyclins. v-Cyclin belongs to Cyclin D subfamily. It contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 131 VCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVLG 210
Cdd:cd20517    16 VCESFELDKNVFPLAVSLLDRLLLKKQGTKETLQKTGAACLLIASKIRTVKPITVSKLTYLSCDCFTNLELINQEKDILE 95

                  ....
gi 1751273124 211 KLKW 214
Cdd:cd20517    96 ALKW 99

first cyclin box found in Arabidopsis thaliana A-type cyclins (CycAs) and similar proteins; Plant A-type cyclins (CycAs) correspond to a group of G2/mitotic-specific cyclins that are functionally linked to S- and M-phases of the mitotic cycle, which predicts their involvement also in meiosis. CycAs associate with their partner cyclin-dependent kinases (CDKs) to trigger the kinase activity. They contain two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20562    51 EVAEEYKLVPDTLYLTVSYIDRFLSGNYVNRQRLQLLGVSCMLIASKYEEICAPQVEEFCYITDNTYTKQEVLEMEIDVL 130

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20562   131 NALQFE 136

first cyclin box found in cyclin-A2 (CCNA2) and similar proteins; CCNA2 controls both the G1/S and the G2/M transition phases of the cell cycle. It is significantly over-expressed in various cancer types, and can be used as a prognostic biomarker for estrogen receptor positive (ER+) breast cancer and tamoxifen resistance. CCNA2 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20561    46 EVGEEYKLQNETLHLAVNYIDRFLSSMSVLRGKLQLVGTAAMLLASKFEEIYPPEVAEFVYITDDTYTKKQVLRMEHLVL 125

                  ....*.
gi 1751273124 210 GKLKWD 215
Cdd:cd20561   126 KVLTFD 131

Cyclin box fold superfamily; The cyclin box is a protein binding domain that functions in cell-cycle and transcriptional control. It is about 100 amino acids in length, composed of five helices, and is present in cyclins, transcription initiation factor IIB (TFIIB), and retinoblastoma tumour suppressor protein (Rb). Cyclins consist of 8 classes of cell cycle regulators that function as regulatory subunits of cyclin-dependent kinases (CDKs), which are serine/threonine kinases. The catalytic activities of CDKs are modulated not only by their interactions with cyclins but also by CDK inhibitors (CKIs). CDKs, cyclins and CKIs play key roles in transcription, epigenetic regulation, metabolism, stem cell self-renewal, neuronal functions, and spermatogenesis. TFIIB is a transcription factor that binds the TATA box. Members in this superfamily contain one or two copies of the cyclin box.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1751273124 129 EEVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLREtTPLTIEKLCIYTDhaVSPRQLRDWE 205
Cdd:cd00043     7 RRLCSKLGLPEEVLELAIELLDRFLSKGLLLGRSPELIAAACLYLACKLEE-LPRTLKEIAKVSG--VSEKELRKAE 80

first cyclin box found in G1/S-specific cyclin-E1 (CCNE1); CCNE1 is essential for the control of the cell cycle at the G1/S (start) transition. It interacts with CDK2 protein kinase to form a serine/threonine kinase holoenzyme complex. CCNE1 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTR-KAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLV 208
Cdd:cd20579    52 EVCEVYKLHRETFYLAQDFFDRFMATQENVvKTRLQLIGISSLFIAAKLEEIYPPKLHQFAYVTDGACTEDEILSMELII 131

                  ....*.
gi 1751273124 209 LGKLKW 214
Cdd:cd20579   132 MKALKW 137

first cyclin box found in G1/S-specific cyclin-E2 (CCNE2); CCNE2 is essential for the control of the cell cycle at the late G1 and early S phase. It interacts with the CDK2 (in vivo) and CDK3 (in vitro) protein kinases to form a serine/threonine kinase holoenzyme complexes. CCNE2 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRY-LSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLV 208
Cdd:cd20580    52 EVCEVYTLHRETFYLAQDFFDRFmLTQKNINKSMLQLIGITSLFIASKLEEIYPPKLHEFAYVTDGACSEDDILDMELII 131

                  ....*.
gi 1751273124 209 LGKLKW 214
Cdd:cd20580   132 LKALKW 137

first cyclin box found in cyclin-O (CCNO) and similar proteins; CCNO is specifically required for generation of multiciliated cells, possibly by promoting a cell cycle state compatible with centriole amplification and maturation. It acts downstream of MCIDAS (multiciliate differentiation and DNA synthesis associated cell cycle protein) to promote mother centriole amplification and maturation in preparation for apical docking. CCNO is involved in the activation of cyclin-dependent kinase 2. CCNO contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20536    11 PVHRHFNLSQETLFLAVNILDRFLATTPVARDCFQLLGVTSLLIACKQEEIYPPEVKDLLALCCGAYTREQICNLECIIL 90

                  ...
gi 1751273124 210 GKL 212
Cdd:cd20536    91 TKL 93

first cyclin box found in G2/mitotic-specific cyclin-B2 (CCNB2) and similar proteins; CCNB2 is essential for the control of the cell cycle at the G2/M (mitosis) transition. It is required for progression through meiosis. CCNB2 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1751273124 139 EEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVLGKLKW 214
Cdd:cd20566    58 QETLYMCVAIMDRFLQVQPVSRKKLQLVGVTALLLASKYEEMYSPEIGDFVYITDNAYTKAQIREMEMLILKELNF 133

first cyclin box found in yeast B-type cyclins; This subfamily includes Saccharomyces cerevisiae G2/mitotic-specific cyclins 1-4 (ScCLB1-4), S-phase entry cyclins 5-6 (ScCLB5-6), and Schizosaccharomyces pombe G2/mitotic-specific cyclins, cig1, cig2 and cdc13. ScCLB1-4 are essential for the control of the cell cycle at the G2/M (mitosis) transition. They interact with the CDC2 protein kinase to form maturation promoting factor (MPF). ScCLB5-6 interact with CDC28 and are involved in DNA replication in Saccharomyces cerevisiae. ScCLB5 is required for efficient progression through S phase and possibly for the normal progression through meiosis. ScCLB6 is involved in G1/S and or S phase progression. Cig1 is required for efficient passage of the G1/S transition. Cig2 and cdc13 are essential for the control of the cell cycle at the G2/M and G1/S (mitosis) transitions. They interact with the cdc2 protein kinase to form MPF. Members in this family contain two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 130 EVCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLTIEKLCIYTDHAVSPRQLRDWEVLVL 209
Cdd:cd20568    50 EVHEKFRLLPETLFLAVNIIDRFLSKRVVSLNKLQLVGISALFIASKYEEVNSPSIKNFAYMTDGAYTVEDILRAERYML 129

                  ....*
gi 1751273124 210 GKLKW 214
Cdd:cd20568   130 NTLEF 134

cyclin box found in Saccharomyces cerevisiae G1/S-specific cyclins (ScCLNs) and similar proteins; ScCLNs, including ScCLN1-3, are essential for the control of the cell cycle at the G1/S (start) transition in Saccharomyces. ScCLN1 and ScCLN2 interact with the CDC28 protein kinase to form maturation promoting factor (MPF). ScCLN3 may be an upstream activator of the G1 cyclins that directly initiate G1/S transition. This family also includes Schizosaccharomyces pombe cyclin puc1, which contributes to negative regulation of the timing of sexual development in fission yeast, and functions at the transition between cycling and non-cycling cells. It interacts with protein kinase A. Members of this family contain one cyclin box. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1751273124 141 VFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTP--LTIEKLCIYTDHAVSPRQLRDWEVLVLGKLKWD 215
Cdd:cd20559    19 TFFLSVNLIDRYCSKRIVLKKHYQLVGCTCLWIASKFWESKArvPLLSELSKMCCNSYGEELFIQMEMHILNTLNWD 95

first cyclin box found in cyclin-J (CCNJ) family; The CCNJ family includes two cyclins, CCNJ and CCNJ-like. CCNJ may regulate the cell cycle or transcription. Members of this family contain two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 131 VCEEQRCEEEVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRETTPLT--IEKLCIYTD-HAVSPRQLRDWEVL 207
Cdd:cd20528    17 VSERLKLSDTTLHLAVYLLDRFMDRYDISEDQLHLVALTCLLLAAKFEELDDNIpkISDLNRYLCnSVYSKQEYLQMELL 96

                  ....*..
gi 1751273124 208 VLGKLKW 214
Cdd:cd20528    97 ILEFFQW 103

second cyclin box found in cyclin-O (CCNO) and similar proteins; This subfamily is composed of CCNO and similar proteins including Schizosaccharomyces pombe meiosis-specific cyclin rem1, Drosophila melanogaster G2/mitotic-specific cyclin-A (CCNA), and Candida albicans G1/S-specific cyclin CCN1, among others. Rem1 is required for pre-meiotic DNA synthesis and S phase progression. CCNA is essential for the control of the cell cycle at the G2/M (mitosis) transition. CCN1 is essential for the control of the cell cycle at the G1/S (start) transition and for maintenance of filamentous growth. CCNO is specifically required for generation of multiciliated cells, possibly by promoting a cell cycle state compatible with centriole amplification and maturation. It is involved in the activation of cyclin-dependent kinase 2. Members of this subfamily contain two cyclin boxes. This model corresponds to the second one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 221 AHDFLALILHRLSLPRDRQALvkkhAQTFLALCATDYTFAMYPPSMIATGSIgaavqgLGACSMSGDE--LTELLAGITG 298
Cdd:cd20537     3 PLSFLRRYLSLLGLDEKVRHL----ARYLLELSLLDYEFLKYRPSLIAAAAL------YLARKILGEPppSPQLLQLVTG 72

                          90
                  ....*....|...
gi 1751273124 299 TEVDCLRACQEQI 311
Cdd:cd20537    73 YSENDLQECAKEL 85

cyclin box found in the cyclin-G (CCNG) family; The CCNG family includes two cyclins, CCNG1 and CCNG2. CCNG1 is the only cyclin that has either positive or negative effects on cell growth. It is associated with G2/M phase arrest in response to DNA damage. It is also involved in the development of human carcinoma. CCNG2 may play a role in growth regulation and in negative regulation of cell cycle progression. It has been identified as a tumor suppressor in several cancers. Members of this family contain one cyclin box. The cyclin box is a protein binding domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 1751273124 140 EVFPLAMNYLDRYLSCVPTRKAQLQLLGAVCMLLASKLRET 180
Cdd:cd20523    20 ETFALAVNLLDRFLSKVKVKPKHLACITVSCFHIAIKSVEE 60

second cyclin box found in Arabidopsis thaliana B-type cyclins (CycBs) and similar proteins; Plant B-type cyclins (CycBs) correspond to a group of G2/mitotic-specific cyclins that are functionally linked to S- and M-phases of the mitotic cycle, which predicts their involvement also in meiosis. CycBs associate with their partner cyclin-dependent kinases (CDKs) to trigger the kinase activity. They contain two cyclin boxes. This model corresponds to the second one. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1751273124 249 FLA-LCATDYTFAMYPPSMIATGSIGAAVQGLGACSmsgdELTELLAGITGTEVDCLRACqeqieAALRESLREAAQTSS 327
Cdd:cd20511    26 FLVeLGLVEYEMLKYSPSMLAASAVYTARCTLNKTP----EWTSTLEFHTGYSESQLMEC-----ARLMVRLHSKAGTGK 96