CLB5/YPR120C Summary Help

Standard Name CLB5 1
Systematic Name YPR120C
Feature Type ORF, Verified
Description B-type cyclin involved in DNA replication during S phase; activates Cdc28p to promote initiation of DNA synthesis; functions in formation of mitotic spindles along with Clb3p and Clb4p; most abundant during late G1 phase; CLB5 has a paralog, CLB6, that arose from the whole genome duplication (1, 2, 3, 4 and see Summary Paragraph)
Name Description CycLin B 1
Chromosomal Location
ChrXVI:775182 to 773875 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All CLB5 GO evidence and references
  View Computational GO annotations for CLB5
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 11 genes
Classical genetics
Large-scale survey
347 total interaction(s) for 203 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 26
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 14
  • Biochemical Activity: 8
  • FRET: 1
  • Protein-RNA: 1
  • Reconstituted Complex: 6
  • Two-hybrid: 6

Genetic Interactions
  • Dosage Lethality: 5
  • Dosage Rescue: 13
  • Negative Genetic: 110
  • Phenotypic Enhancement: 40
  • Phenotypic Suppression: 14
  • Positive Genetic: 27
  • Synthetic Growth Defect: 25
  • Synthetic Lethality: 31
  • Synthetic Rescue: 18

Expression Summary
Length (a.a.) 435
Molecular Weight (Da) 50,431
Isoelectric Point (pI) 7.03
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXVI:775182 to 773875 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1308 775182..773875 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 SGDIDS000006324

CLB5 encodes a B-type cyclin that activates Cdc28p to promote initiation of DNA synthesis. 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 (5). 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 (6). 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 (5). With the exception of CLN3, there are pairs of homologous cyclin genes that share common functions (5, 7). A clb5 clb6 double mutant strain exhibits dramatic delays in DNA replication, suggesting both Clb5p and Clb6p promote progression into S phase (1). CLB5 and CLB6 transcripts are expressed periodically throughout the cell cycle and are most abundant during late G1 (1, 3). Both CLB5 and CLB6 promoters contain MCB (MluI cell cycle box) motifs, which are elements found in several DNA synthesis genes. The transcriptional activator MBF (MCB-binding factor), which is comprised of the Mbp1 and Swi6 proteins, bind to the MCB elements to activate transcription (5). There are excellent reviews by Lew et al.(5) and Mendenhall and Hodge (2) 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 CLB5
1) Schwob E and Nasmyth K  (1993) CLB5 and CLB6, a new pair of B cyclins involved in DNA replication in Saccharomyces cerevisiae. Genes Dev 7(7A):1160-75
2) 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
3) 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
4) 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
5) 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
6) 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
7) Kuntzel H, et al.  (1996) Cell cycle control and initiation of DNA replication in Saccharomyces cerevisiae. Biol Chem 377(7-8):481-7