Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-170
Biochem J 2006 Oct 01;3991:169-75. doi: 10.1042/BJ20060678.
Show Gene links Show Anatomy links

Protein phosphatase 1 regulates the stability of the circadian protein PER2.

Gallego M , Kang H , Virshup DM .


???displayArticle.abstract???
The circadian clock is regulated by a transcription/translation negative feedback loop. A key negative regulator of circadian rhythm in mammals is the PER2 (mammalian PERIOD 2) protein. Its daily degradation at the end of the night accompanies de-repression of transcription. CKI (casein kinase I ) has been identified as the kinase that phosphorylates PER2, targeting it for ubiquitin-mediated proteasomal degradation. We now report that PER2 degradation is also negatively regulated by PP1 (protein phosphatase 1)-mediated dephosphorylation. In Xenopus egg extract, PP1 inhibition by Inhibitor-2 accelerated mPER2 degradation. Co-immunoprecipitation experiments showed that PER2 bound to PP1c in transfected HEK-293 cells. PP1 immunoprecipitated from HEK-293 cells, mouse liver and mouse brain, dephosphorylated CKI-phosphorylated PER2, showing that PER2 is a substrate for mammalian endogenous PP1. Moreover, over-expression of the dominant negative form of PP1c, the D95N mutant, accelerated ubiquitin and proteasome-mediated degradation of PER2, and shortened the PER2 half-life in HEK-293 cells. Over-expression of the PP1 inhibitors, protein phosphatase 1 holoenzyme inhibitor-1 and Inhibitor-2, confirmed these results. Thus PP1 regulates PER2 stability and is therefore a candidate to regulate mammalian circadian rhythms.

???displayArticle.pubmedLink??? 16813562
???displayArticle.pmcLink??? PMC1570171
???displayArticle.link??? Biochem J
???displayArticle.grants??? [+]

Species referenced: Xenopus
Genes referenced: clock csnk1g2 npy4r per2

References [+] :
Cegielska, T-antigen kinase inhibits simian virus 40 DNA replication by phosphorylation of intact T antigen on serines 120 and 123. 1994, Pubmed