Neuronal Cdc2-like Protein Kinase (Cdk5/p25) Is Associated with Protein Phosphatase 1 and Phosphorylates Inhibitor-2

  • Agarwal-Mawal A
  • Paudel H
  • 15

    Readers

    Mendeley users who have this article in their library.
  • 44

    Citations

    Citations of this article.

Abstract

Protein phosphatase 1 (PP1) is complexed with inhibitor 2 (I-2) in the cytosol. In rabbit muscle extract PP1.I-2 is activated upon preincubation with ATP/Mg. This activation is caused by phosphorylation of I-2 on Thr(72) by glycogen synthase kinase 3 (GSK3). We have found that PP1.I-2 in bovine brain extract is also activated upon preincubation with ATP/Mg. However, blocking GSK3 action by LiCl inhibited only approximately 29% of PP1 activity and indicated that GSK3 is not the sole PP1.I-2 activator in the brain. When bovine brain extract was analyzed by gel filtration PP1.I-2 and neuronal Cdc2-like protein kinase (NCLK), a heterodimer of Cdk5 and the regulatory p25 subunit, co-eluted as a approximately 450-kDa size species. The NCLK from the eluted column fractions bound to PP1-specific microcystin-Sepharose and glutathione S-transferase (GST)-I-2-coated glutathione-agarose beads. Similarly, PP1 from the eluted column fractions was pulled down with GST-Cdk5-coated glutathione-agarose beads. In vitro, NCLK phosphorylated I-2 on Thr(72) and activated PP1.I-2 in an ATP/Mg-dependent manner. NCLK bound to PP1 through its Cdk5 subunit and the PP1 binding region was localized to Cdk5 residues 28-41. Our data demonstrate that in brain extract PP1.I-2 and NCLK are associated within a complex of approximately 450 kDa and suggest that NCLK is one of the PP1.I-2-activating kinases in the mammalian brain.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Authors

  • Alka Agarwal-Mawal

  • Hemant K. Paudel

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free