TY - JOUR
T1 - Phosphorylation of Cdc20/Fizzy negatively regulates the mammalian cyclosome/APC in the mitotic checkpoint
AU - Yudkovsky, Yana
AU - Shteinberg, Michal
AU - Listovsky, Tamar
AU - Brandeis, Michael
AU - Hershko, Avram
N1 - Funding Information:
We thank Clara Segal for skillful technical assistance. This research was supported by a United States–Israel Binational Science Foundation (BSF) grant to A.H. and by BSF and Israel Science Foundation grants to M.B.
PY - 2000/5/10
Y1 - 2000/5/10
N2 - The cyclosome/anaphase promoting complex (APC) is a multisubunit ubiquitin ligase that targets mitotic regulators for degradation in exit from mitosis. It is activated at the end of mitosis by phosphorylation and association with the WD-40 protein Cdc20/Fizzy and is then kept active in the G1 phase by association with Cdh1/Hct1. The mitotic checkpoint system that keeps cells with defective spindles from leaving mitosis interacts with Cdc20 and prevents its stimulatory action on the cyclosome. The activity of Cdh1 is negatively regulated by phosphorylation, while the abundance of Cdc20 is cell cycle regulated, with a peak in M-phase. Cdc20 is also phosphorylated in G2/M and in mitotically arrested cells, but the role of phosphorylation remained unknown. Here we show that phosphorylation of Cdc20 by Cdk1/cyclin B abrogates its ability to activate cyclosome/APC from mitotic HeLa cells. A nonphosphorylatable derivative of Cdc20 stimulates cyclin-ubiquitin ligation in extracts from nocodazole-arrested cells to a much greater extent than does wildtype Cdc20. It is suggested that inhibitory phosphorylation of Cdc20/Fizzy may have a role in keeping the cyclosome inactive in early mitosis and under conditions of mitotic checkpoint arrest. (C) 2000 Academic Press.
AB - The cyclosome/anaphase promoting complex (APC) is a multisubunit ubiquitin ligase that targets mitotic regulators for degradation in exit from mitosis. It is activated at the end of mitosis by phosphorylation and association with the WD-40 protein Cdc20/Fizzy and is then kept active in the G1 phase by association with Cdh1/Hct1. The mitotic checkpoint system that keeps cells with defective spindles from leaving mitosis interacts with Cdc20 and prevents its stimulatory action on the cyclosome. The activity of Cdh1 is negatively regulated by phosphorylation, while the abundance of Cdc20 is cell cycle regulated, with a peak in M-phase. Cdc20 is also phosphorylated in G2/M and in mitotically arrested cells, but the role of phosphorylation remained unknown. Here we show that phosphorylation of Cdc20 by Cdk1/cyclin B abrogates its ability to activate cyclosome/APC from mitotic HeLa cells. A nonphosphorylatable derivative of Cdc20 stimulates cyclin-ubiquitin ligation in extracts from nocodazole-arrested cells to a much greater extent than does wildtype Cdc20. It is suggested that inhibitory phosphorylation of Cdc20/Fizzy may have a role in keeping the cyclosome inactive in early mitosis and under conditions of mitotic checkpoint arrest. (C) 2000 Academic Press.
UR - http://www.scopus.com/inward/record.url?scp=0034630750&partnerID=8YFLogxK
U2 - 10.1006/bbrc.2000.2622
DO - 10.1006/bbrc.2000.2622
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C2 - 10799291
AN - SCOPUS:0034630750
SN - 0006-291X
VL - 271
SP - 299
EP - 304
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -