CLB2/YPR119W Summary Help

Standard Name CLB2 1
Systematic Name YPR119W
Feature Type ORF, Verified
Description B-type cyclin involved in cell cycle progression; activates Cdc28p to promote the transition from G2 to M phase; accumulates during G2 and M, then targeted via a destruction box motif for ubiquitin-mediated degradation by the proteasome; CLB2 has a paralog, CLB1, that arose from the whole genome duplication (1, 2, 3, 4, 5 and see Summary Paragraph)
Name Description CycLin B 1
Chromosomal Location
ChrXVI:771653 to 773128 | ORF Map | GBrowse
Gene Ontology Annotations All CLB2 GO evidence and references
  View Computational GO annotations for CLB2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 12 genes
Classical genetics
Large-scale survey
426 total interaction(s) for 210 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 52
  • Affinity Capture-RNA: 4
  • Affinity Capture-Western: 41
  • Biochemical Activity: 17
  • Co-purification: 1
  • FRET: 1
  • Protein-RNA: 1
  • Reconstituted Complex: 11
  • Two-hybrid: 12

Genetic Interactions
  • Dosage Growth Defect: 4
  • Dosage Lethality: 23
  • Dosage Rescue: 15
  • Negative Genetic: 125
  • Phenotypic Enhancement: 13
  • Phenotypic Suppression: 8
  • Positive Genetic: 23
  • Synthetic Growth Defect: 31
  • Synthetic Lethality: 33
  • Synthetic Rescue: 11

Expression Summary
Length (a.a.) 491
Molecular Weight (Da) 56,246
Isoelectric Point (pI) 6.71
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXVI:771653 to 773128 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1476 771653..773128 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 SGDIDS000006323

CLB2 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). CLB1 and CLB2 both promote cell cycle progression into mitosis (6). The CLBs are regulated both transcriptionally and post-translationally (6, 9). CLB1 and CLB2 transcripts accumulate during G2 and M, and their transcription is repressed by the end of mitosis (3, 10). Clb1 and Clb2 proteins are degraded at the end of mitosis as well (6, 9). The Clb proteins contain a destruction box motif in their amino termini, which targets them for ubiquitin-mediated degradation by the proteasome (11). Expression studies indicate that Clb1p is the primary cyclin for the regulation of meiosis while Clb2p is involved only in mitosis (12). It was inititally proposed that the Clb proteins play a role in the degradation of the G1 cyclins (13), but it was later shown that G1 cyclins are unstable in G1 phase, and Clb activity is not required for their degradation (14). 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: 2000-04-04 Contact SGD

References cited on this page View Complete Literature Guide for CLB2
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) Ghiara JB, et al.  (1991) A cyclin B homolog in S. cerevisiae: chronic activation of the Cdc28 protein kinase by cyclin prevents exit from mitosis. Cell 65(1):163-74
3) 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
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) Deshaies RJ  (1997) Phosphorylation and proteolysis: partners in the regulation of cell division in budding yeast. Curr Opin Genet Dev 7(1):7-16
10) Spellman PT, et al.  (1998) Comprehensive identification of cell cycle-regulated genes of the yeast Saccharomyces cerevisiae by microarray hybridization. Mol Biol Cell 9(12):3273-97
11) Seufert W, et al.  (1995) Role of a ubiquitin-conjugating enzyme in degradation of S- and M-phase cyclins. Nature 373(6509):78-81
12) Grandin N and Reed SI  (1993) Differential function and expression of Saccharomyces cerevisiae B-type cyclins in mitosis and meiosis. Mol Cell Biol 13(4):2113-25
13) Blondel M and Mann C  (1996) G2 cyclins are required for the degradation of G1 cyclins in yeast. Nature 384(6606):279-82
14) Schneider BL, et al.  (1998) Yeast G1 cyclins are unstable in G1 phase. Nature 395(6697):86-9