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497  structures 1941  species 0  interactions 79900  sequences 754  architectures

Clan: Cyclin (CL0065)


Cyclin-like superfamily Add an annotation

This Clan contains cyclins, Transcription factor IIB (TFIIB), and the Retinoblastoma tumour suppressor proteins. These were predicted to be related by sequence [1].

This clan contains 12 families and the total number of domains in the clan is 79900. The clan was built by A Bateman.

Literature references

  1. Gibson TJ, Thompson JD, Blocker A, Kouzarides T; , Nucleic Acids Res 1994;22:946-952.: Evidence for a protein domain superfamily shared by the cyclins, TFIIB and RB/p107. PUBMED:8152925 EPMC:8152925
  2. Noble ME, Endicott JA, Brown NR, Johnson LN; , Trends Biochem Sci 1997;22:482-487.: The cyclin box fold: protein recognition in cell-cycle and transcription control. PUBMED:9433129 EPMC:9433129


This clan contains the following 12 member families:

CDK5_activator Cyclin Cyclin_C Cyclin_C_2 Cyclin_N DUF3452 Herp-Cyclin K-cyclin_vir_C RB_A RB_B TFIIB TFIIB_C_1

External database links

Domain organisation

Below is a listing of the unique domain organisations or architectures from this clan. More...

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The table below shows the number of occurrences of each domain throughout the sequence database. More...

Pfam family Num. domains Alignment
Cyclin_N (PF00134) 33915 (42.4%) View
Cyclin_C (PF02984) 16952 (21.2%) View
TFIIB (PF00382) 11997 (15.0%) View
Cyclin (PF08613) 7248 (9.1%) View
RB_A (PF01858) 2480 (3.1%) View
RB_B (PF01857) 2380 (3.0%) View
DUF3452 (PF11934) 2058 (2.6%) View
Cyclin_C_2 (PF16899) 1833 (2.3%) View
CDK5_activator (PF03261) 1010 (1.3%) View
TFIIB_C_1 (PF18542) 18 (0.0%) View
K-cyclin_vir_C (PF09080) 6 (0.0%) View
Herp-Cyclin (PF09241) 3 (0.0%) View
Total: 12 Total: 79900 Clan alignment

Please note: Clan alignments can be very large and can cause problems for some browsers. Read the note above before viewing.

Family relationships

This diagram shows the relationships between members of this clan. More...

Species distribution

Tree controls


This tree shows the occurrence of the domains in this clan across different species. More...



For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the MSD group, to allow us to map Pfam domains onto UniProt three-dimensional structures. The table below shows the mapping between the Pfam families in this clan, the corresponding UniProt entries, and the region of the three-dimensional structures that are available for that sequence.

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