Phosphorylation of phosphoprotein phosphatase inhibitor-2 (I-2) in rat fat cells.
Fat cells were incubated with 32Pi for 2 h before the [32P]I-2 was immunoprecipitated, subjected to SDS/PAGE, and detected by autoradiography. [32P]I-2 (Mr = 32,000) was not recovered when excess purified I-2 was added with the antiserum or when nonimmune serum was used. Immunoprecipitated I-2 was heat-stable, inhibited phosphatase activity, and could be synergistically phosphorylated by casein kinase II and FA/GSK-3. Several times more [32P]phosphoserine than [32P]phosphothreonine was found in I-2 from 32P-labeled cells. Insulin increased the 32P-content of I-2 by as much as 40%, suggesting that phosphorylation of I-2 might be involved in the effect of insulin on stimulating protein dephosphorylation.
Lawrence
J C
JC
Department of Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110.
Hiken
J
J
Burnette
B
B
DePaoli-Roach
A A
AA
D000255:Adenosine Triphosphate / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D001345:Autoradiography; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D047388:Casein Kinases; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D007163:Immunosorbent Techniques; D007328:Insulin / Q000494:pharmacology; D008297:Male; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D000097847:Protein Phosphatase Inhibitory Proteins
D000255:Adenosine Triphosphate; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D047388:Casein Kinases; D007328:Insulin; D011494:Protein Kinases; D011506:Proteins; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins