Activation of type‐1 protein phosphatase by cdc2 kinase

[摘要]

Purified cdc2 or cdc2 obtained from HeLa cells in association with p131^sucl activate inactive type-1 protein phosphatase (PP1) (catalytic subunit · inhibitor-2 complex, purified from skeletal muscle). Likewise in the case of PP1 activation by F_A/GSK3, activation by cdc2 is accompanied by phosphorylation of inhibitor-2 (I2) and free I2 can be phosphorylated as well. Correlation between PP1 activation and 12 phosphorylation is suggested by the fact that both activation and phosphorylation (a) increase in parallel during incubation with cdc2, (b) decrease in parallel upon subsequent cdc2 inhibition by EDTA, and (c) are inhibited by the cdc2 inhibitor 5,6-dichlorobenzimidazole riboside. cdc2 also phosphorylates the catalytic subunit of PP1, whether in the complex with I2 or as free molecule. The activation of PPI by cdc2 and by F_A/GSK3 is compared.

[学科分类] 生物化学/生物物理

[关键词] Protein phosphatase;Protein kinase;Phosphorylation;Cell cycle;TPCK;N-tosyl-l-phenylalanine chloromethyl ketone;PMSF;phenylmethylsulfonyl fluoride;2-ME;2-mercaptoethanol;DTT;dithiothreitol;DRB;5;6-dichlorobenzimidazole riboside;HEPES;N-[2-hydroxyethyl]piperazine-N′-[ethanesulfonic acid];BSA;bovine serum albumin;SDS;sodium dodecyl sulfate;DMEM;Dulbecco's Modified Eagle Medium;PP1;protein phosphatase of type-1;Ea;active catalytic subunit of PP1;Ei;inactive catalytic subunit of PP1;Ei · 12;inactive cytosolic PP1 complex;I2;inhibitor-2 of PP1;FA/ GSK3;protein kinase that activates PP1;also called glycogen synthase kinase-3;cdc2;cyclin-dependent serine kinase that is activated at the G2/M transition of cell cycle