# BUB1B

Source: https://onco.cc/targets/bub1b/  
OnCo record `bub1b` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

BUB1B (Mitotic checkpoint serine/threonine-protein kinase BUB1 beta) is a protein kinase, an enzyme that switches other proteins on by adding phosphate groups. In the public catalogues the evidence so far is association rather than a proven role. Tied to Colorectal cancer, Skin cancer, Breast cancer and 3 more.

## Summary

Kinase which is a component of the mitotic checkpoint complex (MCC), which inhibits APC/C and delays chromosome segregation until all chromosomes are properly attached to the mitotic spindle. The MCC, which consists of CDC20, MAD2L1/MAD2, BUB1B/BUBR1 and BUB3, is a key player of the spindle assembly checkpoint. The MCC-bound APC/C complex is inactive and this delays the metaphase/anaphase transition.

Open Targets scores its association with cancer at 0.77 (direct and indirect evidence; datatypes genetic literature 0.68, literature 0.98, genetic association 0.55, somatic mutation 0.89, animal model 0.61).

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: BUB1 mitotic checkpoint serine/threonine kinase B; Mitotic checkpoint serine/threonine-protein kinase BUB1 beta; BUBR1; MAD3L; Bub1A; SSK1
- Tags: cancer-genes-wave
- Symbol: BUB1B
- Class: kinase
- Biology: Kinase which is a component of the mitotic checkpoint complex (MCC), which inhibits APC/C and delays chromosome segregation until all chromosomes are properly attached to the mitotic spindle. The MCC, which consists of CDC20, MAD2L1/MAD2, BUB1B/BUBR1 and BUB3, is a key player of the spindle assembly checkpoint. The MCC-bound APC/C complex is inactive and this delays the metaphase/anaphase transition. When the spindle assembly checkpoint is silenced, the MCC-APC/C complex recruits the E2 enzyme UBCH10 and triggers the auto-ubiquitination of CDC20 in the MCC, thereby reactivating APC/C for transition into anaphase. MCC also monitors kinetochore activities that depend on the kinetochore motor CENPE. Required for kinetochore localisation of CENPE. Location: Cytoplasm; Nucleus; Chromosome, centromere, kinetochore; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome (UniProt). Locus 15q15.1 (HGNC).
- Where found: Colorectal cancer: Open Targets association 0.57 with colorectal cancer (MONDO_0005575); Skin cancer: Open Targets association 0.55 with skin cancer (MONDO_0002898); Breast cancer: Open Targets association 0.53 with breast cancer (MONDO_0007254); Ovarian cancer: Open Targets association 0.51 with ovarian cancer (MONDO_0008170); Gastric & gastro-oesophageal junction cancer: Open Targets association 0.50 with gastric cancer (MONDO_0001056); Melanoma: Open Targets association 0.52 with melanoma (MONDO_0005105)

## Notes

- Written by scripts/fetch-cancer-genes.ts from CIViC, Open Targets, IntOGen, HGNC and UniProt; the function text is UniProt's, condensed and in UK spelling. Roles: none stated by the sources. Evidence tier "association-only" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:1149: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:1149
- UniProt O60566: https://www.uniprot.org/uniprotkb/O60566/entry
- NCBI Gene 701: https://www.ncbi.nlm.nih.gov/gene/701
- Ensembl ENSG00000156970: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156970

## Connected records

- collections: [Open Targets Platform](https://onco.cc/collections/open-targets/)
- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Gastric & gastro-oesophageal junction cancer](https://onco.cc/cancers/gastric/), [Melanoma](https://onco.cc/cancers/melanoma/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Skin cancer (all types)](https://onco.cc/cancers/skin-cancer/)
- pathways: [Mitosis & the spindle assembly checkpoint](https://onco.cc/pathways/mitotic-spindle-checkpoint/)

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JSON: https://onco.cc/api/v1/entities/bub1b.json