PP1-mediated dephosphorylation of phosphoproteins at mitotic exit is controlled by inhibitor-1 and PP1 phosphorylation.

Journal Article (Journal Article)

Loss of cell division cycle 2 (Cdc2, also known as Cdk1) activity after cyclin B degradation is necessary, but not sufficient, for mitotic exit. Proteins phosphorylated by Cdc2 and downstream mitotic kinases must be dephosphorylated. We report here that protein phosphatase-1 (PP1) is the main catalyst of mitotic phosphoprotein dephosphorylation. Suppression of PP1 during early mitosis is maintained through dual inhibition by Cdc2 phosphorylation and the binding of inhibitor-1. Protein kinase A (PKA) phosphorylates inhibitor-1, mediating binding to PP1. As Cdc2 levels drop after cyclin B degradation, auto-dephosphorylation of PP1 at its Cdc2 phosphorylation site (Thr 320) allows partial PP1 activation. This promotes PP1-regulated dephosphorylation at the activating site of inhibitor-1 (Thr 35) followed by dissociation of the inhibitor-1-PP1 complex and then full PP1 activation to promote mitotic exit. Thus, Cdc2 both phosphorylates multiple mitotic substrates and inhibits their PP1-mediated dephosphorylation.

Full Text

Duke Authors

Cited Authors

  • Wu, JQ; Guo, JY; Tang, W; Yang, C-S; Freel, CD; Chen, C; Nairn, AC; Kornbluth, S

Published Date

  • May 2009

Published In

Volume / Issue

  • 11 / 5

Start / End Page

  • 644 - 651

PubMed ID

  • 19396163

Pubmed Central ID

  • PMC2788612

Electronic International Standard Serial Number (EISSN)

  • 1476-4679

International Standard Serial Number (ISSN)

  • 1465-7392

Digital Object Identifier (DOI)

  • 10.1038/ncb1871


  • eng