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Proteolysis of γ‐tubulin small complex proteins is mediated by the ubiquitin‐proteasome system
Author(s) -
Yin Can,
Lui Edna S. W.,
Jiang Taolue,
Qi Robert Z.
Publication year - 2021
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.14146
Subject(s) - cullin , tubulin , proteasome , proteolysis , ubiquitin , microbiology and biotechnology , microtubule , biology , tetramer , microtubule nucleation , degron , biochemistry , chemistry , centrosome , ubiquitin ligase , cell cycle , cell , enzyme , gene
Microtubule nucleation is mainly mediated by the γ‐tubulin ring complex (γTuRC), whose core components are γ‐tubulin and γ‐tubulin complex proteins GCP2–6. A substantial fraction of γ‐tubulin also exists with GCP2 and GCP3 in a tetramer called the γ‐tubulin small complex (γTuSC). To date, the mechanisms underlying the turnover of γ‐tubulin and GCPs have remained unclear. Here, we show that γ‐tubulin, GCP2, and GCP3 are proteolyzed by the ubiquitin‐proteasome system, and we identify cullin 1, cullin 4A, and cullin 4B as the E3 ligases that mediate the ubiquitination and, consequently, the degradation of γ‐tubulin. Notably, we found that γTuSC disassembly promotes the degradation of γ‐tubulin, GCP2, and GCP3, which indicates a role for γTuSCs in the stabilization of its components.