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Mol Biol Cell 2022 Oct 01;3312:ar115. doi: 10.1091/mbc.E22-04-0118.
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Revisiting the multisite phosphorylation that produces the M-phase supershift of key mitotic regulators.

Tan T , Wu C , Liu B , Pan BF , Hawke DH , Su Z , Liu S , Zhang W , Wang R , Lin SH , Kuang J .

The term M-phase supershift denotes the phosphorylation-dependent substantial increase in the apparent molecular weight of numerous proteins of varied biological functions during M-phase induction. Although the M-phase supershift of multiple key mitotic regulators has been attributed to the multisite phosphorylation catalyzed by the Cdk1/cyclin B/Cks complex, this view is challenged by multiple lines of paradoxical observations. To solve this problem, we reconstituted the M-phase supershift of Xenopus Cdc25C, Myt1, Wee1A, APC3, and Greatwall in Xenopus egg extracts and characterized the supershift-producing phosphorylations. Our results demonstrate that their M-phase supershifts are each due to simultaneous phosphorylation of a considerable portion of S/T/Y residues in a long intrinsically disordered region that is enriched in both S/T residues and S/TP motifs. Although the major mitotic kinases in Xenopus egg extracts, Cdk1, MAPK, Plx1, and RSK2, are able to phosphorylate the five mitotic regulators, they are neither sufficient nor required to produce the M-phase supershift. Accordingly, inhibition of the four major mitotic kinase activities in Xenopus oocytes did not inhibit the M-phase supershift in okadaic acid-induced oocyte maturation. These findings indicate that the M-phase supershift is produced by a previously unrecognized category of mitotic phosphorylation that likely plays important roles in M-phase induction.

PubMed ID: 35976701
PMC ID: PMC9635296
Article link: Mol Biol Cell
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: cdc25c cdk1 map2k1 mapk1 mastl myc myt1 pin1 plk1 rps6ka3 wee1
GO keywords: mitotic M phase [+]

Article Images: [+] show captions
References [+] :
Abe, The initial phase of chromosome condensation requires Cdk1-mediated phosphorylation of the CAP-D3 subunit of condensin II. 2011, Pubmed