Insulin and insulin antagonists evoke phosphorylation of P20 at serine 157 and serine 16 respectively in rat skeletal muscle.
We show here that insulin and insulin antagonists differentially modify phosphorylation of three phospho-isoforms of P20 (termed S1, S2 and S3) in rat skeletal muscle. Precise phosphorylation sites of S1 and S2 were mapped to serine 157 and serine 16 respectively. Insulin evoked phosphorylation of P20 at serine 157 through the phosphatidylinositol (PI) 3-kinase pathway. Epinephrine and calcitonin gene-related peptide decreased phosphorylation at serine 157 and increased phosphorylation at serine 16 and other unidentified sites. These results demonstrate that the PI-3-kinase pathway of anabolic insulin and the cAMP pathway of catabolic hormones converge on P20 and suggest a potential role of this protein in regulating energy metabolism of skeletal muscle.
Wang
Y
Y
School of Biological Sciences, Level 4, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Xu
A
A
Pearson
R B
RB
Cooper
G J
GJ
D000595:Amino Acid Sequence; D000818:Animals; D004789:Enzyme Activation; D004837:Epinephrine / Q000494:pharmacology; D050886:HSP20 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007329:Insulin Antagonists / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010449:Peptide Mapping; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D012694:Serine / Q000378:metabolism*; D015398:Signal Transduction
D004837:Epinephrine; D050886:HSP20 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007328:Insulin; D007329:Insulin Antagonists; D009124:Muscle Proteins; D019869:Phosphatidylinositol 3-Kinases; D010748:Phosphopeptides; D020033:Protein Isoforms; D012694:Serine; C087458:Hspb6 protein, rat