CLB4/YLR210W Summary Help

Standard Name CLB4 1, 2
Systematic Name YLR210W
Feature Type ORF, Verified
Description B-type cyclin involved in cell cycle progression; activates Cdc28p to promote the G2/M transition; may be involved in DNA replication and spindle assembly; accumulates during S phase and G2, then targeted for ubiquitin-mediated degradation; CLB4 has a paralog, CLB3, that arose from the whole genome duplication (1, 2, 3, 4, 5 and see Summary Paragraph)
Name Description CycLin B 1
Chromosomal Location
ChrXII:562008 to 563390 | ORF Map | GBrowse
Gene Ontology Annotations All CLB4 GO evidence and references
  View Computational GO annotations for CLB4
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 4 genes
Classical genetics
Large-scale survey
113 total interaction(s) for 63 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 5
  • Affinity Capture-RNA: 1
  • Reconstituted Complex: 2
  • Two-hybrid: 3

Genetic Interactions
  • Dosage Growth Defect: 3
  • Dosage Lethality: 1
  • Dosage Rescue: 1
  • Negative Genetic: 50
  • Phenotypic Enhancement: 5
  • Phenotypic Suppression: 2
  • Positive Genetic: 10
  • Synthetic Growth Defect: 19
  • Synthetic Lethality: 11

Expression Summary
Length (a.a.) 460
Molecular Weight (Da) 53,852
Isoelectric Point (pI) 4.61
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXII:562008 to 563390 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1383 562008..563390 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000004200

CLB4 encodes a B-type cyclin that activates Cdc28p to promote the transition from G2 to M phase of the cell cycle. Progression through the cell cycle is a carefully regulated process that is conserved throughout eukaryotes. Periodic activation of cyclin-dependent kinases (CDKs) are required for this process; the critical CDK involved in cell cycle progression in yeast is Cdc28p (6). Cyclins are the regulatory subunits that activate CDKs at the appropriate time in the cell cycle; they were first identified in sea urchins and named for their cyclical accumulation during particular phases of the cell cycle (7). CLN1, CLN2, and CLN3 encode the yeast G1 cyclins while there are 6 B-type cyclins (CLB) genes involved in activation of S, G2, and M phases of the cell cycle (6). With the exception of CLN3, there are pairs of homologous cyclin genes that share common functions (6, 8). Genetic interactions have shown that CLB3 and CLB4 may both be involved in DNA replication and spindle assembly as well as the G2/M-phase transition(3). Recent work demonstrates that Cdc28p-Clb4p facilitates spindle alignment by regulating the interaction of astral microtubules with subdomains of the bud cortex (9).CLB3 and CLB4 transcripts accumulate during S phase and G2 (3). Like the other Clb proteins, Clb3p and Clb4p contain a destruction box motif in their amino termini, which may target them for ubiquitin-mediated degradation by the proteasome (6). It was inititally proposed that the Clb proteins play a role in the degradation of the G1 cyclins (10), but it was later shown that G1 cyclins are unstable in G1 phase, and Clb activity is not required for their degradation (11). There are excellent reviews by Lew et al.(6) and Mendenhall and Hodge (4) that describe cell cycle control in S. cerevisiae in detail.

Last updated: 2006-03-23 Contact SGD

References cited on this page View Complete Literature Guide for CLB4
1) Surana U, et al.  (1991) The role of CDC28 and cyclins during mitosis in the budding yeast S. cerevisiae. Cell 65(1):145-61
2) Fitch I, et al.  (1992) Characterization of four B-type cyclin genes of the budding yeast Saccharomyces cerevisiae. Mol Biol Cell 3(7):805-18
3) Richardson H, et al.  (1992) Cyclin-B homologs in Saccharomyces cerevisiae function in S phase and in G2. Genes Dev 6(11):2021-34
4) Mendenhall MD and Hodge AE  (1998) Regulation of Cdc28 cyclin-dependent protein kinase activity during the cell cycle of the yeast Saccharomyces cerevisiae. Microbiol Mol Biol Rev 62(4):1191-243
5) Byrne KP and Wolfe KH  (2005) The Yeast Gene Order Browser: combining curated homology and syntenic context reveals gene fate in polyploid species. Genome Res 15(10):1456-61
6) Lew DJ, et al.  (1997) "Cell cycle control in Saccharomyces cerevisiae." Pp. 607-695 in The Molecular and Cellular Biology of the Yeast Saccharomyces: Cell Cycle and Cell Biology, edited by Pringle JR, Broach JR and Jones EW. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press
7) Evans T, et al.  (1983) Cyclin: a protein specified by maternal mRNA in sea urchin eggs that is destroyed at each cleavage division. Cell 33(2):389-96
8) Kuntzel H, et al.  (1996) Cell cycle control and initiation of DNA replication in Saccharomyces cerevisiae. Biol Chem 377(7-8):481-7
9) Maekawa H and Schiebel E  (2004) Cdk1-Clb4 controls the interaction of astral microtubule plus ends with subdomains of the daughter cell cortex. Genes Dev 18(14):1709-24
10) Blondel M and Mann C  (1996) G2 cyclins are required for the degradation of G1 cyclins in yeast. Nature 384(6606):279-82
11) Schneider BL, et al.  (1998) Yeast G1 cyclins are unstable in G1 phase. Nature 395(6697):86-9