BUB3/YOR026W Summary Help

Standard Name BUB3 1
Systematic Name YOR026W
Alias PAC9 2
Feature Type ORF, Verified
Description Kinetochore checkpoint WD40 repeat protein; localizes to kinetochores during prophase and metaphase, delays anaphase in the presence of unattached kinetochores; forms complexes with Mad1p-Bub1p and with Cdc20p, binds Mad2p and Mad3p (3, 4, 5, 6 and see Summary Paragraph)
Name Description Budding Uninhibited by Benzimidazole 1
Chromosomal Location
ChrXV:379781 to 380806 | ORF Map | GBrowse
Gene Ontology Annotations All BUB3 GO evidence and references
  View Computational GO annotations for BUB3
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 3 genes
Classical genetics
Large-scale survey
727 total interaction(s) for 414 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 6
  • Affinity Capture-Western: 17
  • Biochemical Activity: 1
  • Co-crystal Structure: 2
  • Co-fractionation: 1
  • Co-localization: 1
  • Reconstituted Complex: 10
  • Two-hybrid: 8

Genetic Interactions
  • Dosage Lethality: 2
  • Dosage Rescue: 4
  • Negative Genetic: 396
  • Phenotypic Enhancement: 11
  • Phenotypic Suppression: 14
  • Positive Genetic: 78
  • Synthetic Growth Defect: 39
  • Synthetic Lethality: 134
  • Synthetic Rescue: 3

Expression Summary
Length (a.a.) 341
Molecular Weight (Da) 38,444
Isoelectric Point (pI) 4.93
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXV:379781 to 380806 | ORF Map | GBrowse
Last Update Coordinates: 2006-01-05 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1026 379781..380806 2006-01-05 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 SGDIDS000005552

BUB3 is a non-essential gene whose product is involved in the spindle checkpoint (1, 7). The spindle checkpoint delays the onset of anaphase in cells with defects in mitotic spindle assembly or in the attachment of chromosomes to the spindle microtubules (see 8 for review; reference 9 describes defects detected by the checkpoint). The checkpoint works by inhibiting the activity of the anaphase promoting complex, thereby preventing the degradation of several cell cycle regulators (8). Bub3p is a substrate for the protein kinase Bub1p (7), and interacts physically with Mad3p (5). Like other spindle checkpoint mutants, bub3 loss-of-function mutants are sensitive to benomyl and cannot delay cell division in response to spindle depolymerization (1). Bub1p, Bub3p, Mad1p, Mad2p, Mad3p, and the protein kinase Mps1p act in a branch of the spindle checkpoint pathway that may prevent premature chromosome disjunction. A second branch involves Bub2p and Bfa1p, and may prevent cytokinesis prior to chromosome segregation (10, 11, 12, 13). Homologs of Bub3p have been identified in several organisms, including Drosophila, mouse and human (BUB3), and most have been shown to localize to kinetochores not attached to spindles (14, 3, 15, 16).

Last updated: 2005-07-01 Contact SGD

References cited on this page View Complete Literature Guide for BUB3
1) Hoyt MA, et al.  (1991) S. cerevisiae genes required for cell cycle arrest in response to loss of microtubule function. Cell 66(3):507-17
2) Geiser JR, et al.  (1997) Saccharomyces cerevisiae genes required in the absence of the CIN8-encoded spindle motor act in functionally diverse mitotic pathways. Mol Biol Cell 8(6):1035-50
3) Martinez-Exposito MJ, et al.  (1999) Retention of the BUB3 checkpoint protein on lagging chromosomes. Proc Natl Acad Sci U S A 96(15):8493-8
4) Brady DM and Hardwick KG  (2000) Complex formation between Mad1p, Bub1p and Bub3p is crucial for spindle checkpoint function. Curr Biol 10(11):675-8
5) Hardwick KG, et al.  (2000) MAD3 encodes a novel component of the spindle checkpoint which interacts with Bub3p, Cdc20p, and Mad2p. J Cell Biol 148(5):871-82
6) Fraschini R, et al.  (2001) Bub3 interaction with Mad2, Mad3 and Cdc20 is mediated by WD40 repeats and does not require intact kinetochores. EMBO J 20(23):6648-59
7) Roberts BT, et al.  (1994) The Saccharomyces cerevisiae checkpoint gene BUB1 encodes a novel protein kinase. Mol Cell Biol 14(12):8282-91
8) Hardwick KG  (1998) The spindle checkpoint. Trends Genet 14(1):1-4
9) Hardwick KG, et al.  (1999) Lesions in many different spindle components activate the spindle checkpoint in the budding yeast Saccharomyces cerevisiae. Genetics 152(2):509-18
10) Alexandru G, et al.  (1999) Sister chromatid separation and chromosome re-duplication are regulated by different mechanisms in response to spindle damage. EMBO J 18(10):2707-21
11) Fesquet D, et al.  (1999) A Bub2p-dependent spindle checkpoint pathway regulates the Dbf2p kinase in budding yeast. EMBO J 18(9):2424-34
12) Fraschini R, et al.  (1999) Budding yeast Bub2 is localized at spindle pole bodies and activates the mitotic checkpoint via a different pathway from Mad2. J Cell Biol 145(5):979-91
13) Li R  (1999) Bifurcation of the mitotic checkpoint pathway in budding yeast. Proc Natl Acad Sci U S A 96(9):4989-94
14) Basu J, et al.  (1998) Localization of the Drosophila checkpoint control protein Bub3 to the kinetochore requires Bub1 but not Zw10 or Rod. Chromosoma 107(6-7):376-85
15) Taylor SS, et al.  (1998) The human homologue of Bub3 is required for kinetochore localization of Bub1 and a Mad3/Bub1-related protein kinase. J Cell Biol 142(1):1-11
16) Goto T and Kinoshita T  (1999) Maternal transcripts of mitotic checkpoint gene, Xbub3, are accumulated in the animal blastomeres of Xenopus early embryo. DNA Cell Biol 18(3):227-34