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 992319659   1 MNDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYARKKVDLTHLEGEVEKRK 80
Cdd:cd20593   29 MNDSLRTDVFVRFNPETIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYTRKKVDLEHLESKVEKRK 108

                         90
                 ....*....|....*
gi 992319659  81 HAIEEAKAQARGLLP 95
Cdd:cd20593  109 LAIEEAKAKAKGLLP 123

second cyclin box found in cyclin-2 (CCNL2) and similar proteins; CCNL2 is a novel RNA polymerase II-associated cyclin that is involved in pre-mRNA splicing. It may induce cell death, possibly by acting on the transcription and RNA processing of apoptosis-related factors. CCNL2 contains 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 992319659   1 MNDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYARKKVDLTHLEGEVEKRK 80
Cdd:cd20593   29 MNDSLRTDVFVRFNPETIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYTRKKVDLEHLESKVEKRK 108

                         90
                 ....*....|....*
gi 992319659  81 HAIEEAKAQARGLLP 95
Cdd:cd20593  109 LAIEEAKAKAKGLLP 123

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
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 992319659   10 FVRFQPESIACACIYLAARTLeiplpNRPHW--FLLF--GATEEEIQEICLKILQLYAR 64
Cdd:pfam02984  39 FLKYPPSLIAAAAVYLARKTL-----NSPEWteTLEHytGYSEEDLKPCVKLLLELLLN 92

second cyclin box found in cyclin-2 (CCNL2) and similar proteins; CCNL2 is a novel RNA polymerase II-associated cyclin that is involved in pre-mRNA splicing. It may induce cell death, possibly by acting on the transcription and RNA processing of apoptosis-related factors. CCNL2 contains 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 992319659   1 MNDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYARKKVDLTHLEGEVEKRK 80
Cdd:cd20593   29 MNDSLRTDVFVRFNPETIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYTRKKVDLEHLESKVEKRK 108

                         90
                 ....*....|....*
gi 992319659  81 HAIEEAKAQARGLLP 95
Cdd:cd20593  109 LAIEEAKAKAKGLLP 123

second cyclin box found in cyclin-L (CCNL) family; The CCNL family includes two cyclins, CCNL1 and CCNL2. CCNL1 is involved in regulation of RNA polymerase II (pol II) transcription. It functions in association with cyclin-dependent kinases (CDKs). CCNL2 is a novel RNA polymerase II-associated cyclin involved in pre-mRNA splicing. It may induce cell death, possibly by acting on the transcription and RNA processing of apoptosis-related factors. Members of this family 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 992319659   1 MNDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYAR 64
Cdd:cd20533   29 MNDSLRTDLCVRYPPEVIACACIYLAARELGIPLPLPPPWWELFDVSKEDIEEICLTILELYTR 92

second cyclin box found in Arabidopsis thaliana L-type cyclins (CycL) and similar proteins; Cyclin-L1-1 (CycL1), also called arginine-rich cyclin 1 (AtRCY1), or protein MODIFIER OF SNC1 12, is the cognate cyclin for cyclin-dependent kinase G1 (CDKG1). It is involved in regulation of DNA methylation and transcriptional silencing. It is required for synapsis and male meiosis, and for the proper splicing of specific resistance (R) genes. L-type cyclins 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 992319659   2 NDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPHWFLLFGATEEEIQEICLKILQLYARKK 66
Cdd:cd20594   31 NDSLRTTLCVRFKSEVVACGVVYAAARRFQVPLPENPPWWKVFDAEKAEIDVVCKVLADLYRQPK 95

second cyclin box found in cyclin-K (CCNK) and similar proteins; CCNK is a novel RNA polymerase II-associated C-type cyclin possessing both carboxy-terminal domain kinase and Cdk-activating kinase activity. It is a regulatory subunit of cyclin-dependent kinases that mediates the activation of these target kinases. It plays a role in transcriptional regulation by controlling the phosphorylation of the C-terminal domain (CTD) of the large subunit of RNA polymerase II (POLR2A). CCNK contains two cyclin boxes. This model corresponds to the second one. The cyclin box is a protein binding domain.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 992319659   2 NDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPH------WFLLF--GATEEEIQEICLKILQLY 62
Cdd:cd20531   33 NDSLCTTLCLQWEPEIIAVALMYLAAKLSKFDLQDWTSkppgkrWWEQFveDVSLEVLEDICHQVLDLY 101

second cyclin box found in cyclin-M (CCNM) family; The CCNM family proteins, also called ancient conserved domain proteins (ACDPs), are evolutionarily conserved Mg2+ transporters. CCNM, also called cyclin-Q (CCNQ), or CDK10-activating cyclin, or cyclin-related protein FAM58A, associates with CDK10 to promote its kinase activity. Members of this family 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 992319659   2 NDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRPH----WFLLF--GATEEEIQEICLKILQLY 62
Cdd:cd20535   36 RDFYHSPLCLQFKPQHIALAVIYLALQVYGVKVPPEEEaekpWWQAFceDLTKETIDEIIEDIINVY 102

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
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 992319659   1 MNDSLRTDVFVRFQPESIACACIYLAARTLEIPLPNRpHWFLLFGATEEEIQEICLK 57
Cdd:cd00043   27 LDRFLSKGLLLGRSPELIAAACLYLACKLEELPRTLK-EIAKVSGVSEKELRKAEKE 82

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
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 992319659   10 FVRFQPESIACACIYLAARTLeiplpNRPHW--FLLF--GATEEEIQEICLKILQLYAR 64
Cdd:pfam02984  39 FLKYPPSLIAAAAVYLARKTL-----NSPEWteTLEHytGYSEEDLKPCVKLLLELLLN 92

second cyclin box found in cyclin-T (CCNT) family; The CCNT family includes two C-type cyclins, cyclin-T1 (CCNT1) and cyclin-T2 (CCNT2), both of which are regulatory subunits of the cyclin-dependent kinase pair (CDK9/cyclin-T) complex, also called positive transcription elongation factor B (P-TEFb), which is proposed to facilitate the transition from abortive to productive elongation by phosphorylating the CTD (C-terminal domain) of the large subunit of RNA polymerase II (RNA Pol II). Members in this family 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 992319659   2 NDSLRTDVFVRFQPESIACACIYLAAR--TLEIPLPNR-PHWFLLF--GATEEEIQEICLKIL 59
Cdd:cd20539   30 NSLHLTTFCLQYKPTVIACVCIHLACKwsNWEIPRSSEgKDWYEYVdpSLTLEELDELTSEFL 92