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APC2 cullin protein and APC11 RING protein comprise the minimal ubiquitin ligase module of the anaphase-promoting complex
被引:152
作者:
Tang, ZY
Li, B
Bharadwaj, R
Zhu, HH
Özkan, E
Hakala, K
Deisenhofer, J
Yu, HT
[1
]
机构:
[1] Univ Texas, SW Med Ctr, Dept Pharmacol, Dallas, TX 75390 USA
[2] Univ Texas, SW Med Ctr, Dept Biochem, Dallas, TX 75390 USA
[3] Univ Texas, SW Med Ctr, Howard Hughes Med Inst, Dallas, TX 75390 USA
关键词:
D O I:
10.1091/mbc.12.12.3839
中图分类号:
Q2 [细胞生物学];
学科分类号:
071009 ;
090102 ;
摘要:
In mitosis, the anaphase-promoting complex (APC) regulates the onset of sister-chromatid separation and exit from mitosis by mediating the ubiquitination and degradation of the securin protein and mitotic cyclins. With the use of a baculoviral expression system, we have reconstituted the ubiquitin ligase activity of human APC. In combination with Ubc4 or UbcH10, a heterodimeric complex of APC2 and APC11 is sufficient to catalyze the ubiquitination of human securin and cyclin B1. However, the minimal APC2/11 ubiquitin ligase module does not possess substrate specificity, because it also ubiquitinates the destruction box deletion mutants of securin and cyclin B1. Both APC11 and UbcH10 bind to the C-terminal cullin homology domain of APC2, whereas Ubc4 interacts with APC11 directly. Zn2+-binding and mutagenesis experiments indicate that APC11 binds Zn2+ at a 1:3 M ratio. Unlike the two Zn2+ ions of the canonical RING-finger motif, the third Zn2+ ion of APC11 is not essential for its ligase activity. Surprisingly, with Ubc4 as the E2 enzyme, Zn2+ ions alone are sufficient to catalyze the ubiquitination of cyclin B1. Therefore, the Zn2+ ions of the RING finger family of ubiquitin ligases may be directly involved in catalysis.
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页码:3839 / 3851
页数:13
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