Regulation of protein phosphatase 1 and 2A activities by insulin during myogenesis in rat skeletal muscle cells in culture.
作者： M. Srinivasan , N. Begum
DOI: 10.1016/S0021-9258(18)99905-9
关键词:
摘要: In this study, we examined protein phosphatase 1 (PP-1) and 2A (PP-2A) activities during various stages of myogenesis their regulation by insulin in rat skeletal muscle cells. Protein were measured using 32P-labeled phosphorylase a, glycogen synthase, kinase as substrates. Spontaneous PP-1 activity increased progressively cultures from 2 to 5 days, PP-2A remained constant days 2-4 sharply on day 5. Most the times culture, a significant proportion (approximately 65%) was form that could be activated trypsin. Insulin stimulated (40-80% increase over basal) time (t1/2 approximately min)- dose (EC50 0.1 nM)-dependent manner. activation accompanied corresponding inhibition activity. The effects differentiation dependent observed only cells at fusion (day 5) post-fusion. insulin's effect correlated with gradual appearance G subunit fusion. Immunoprecipitation an antibody directed against site sequence rabbit PP-1G detected 160-kDa protein, phosphorylation which significantly insulin. This well immunoprecipitated Treatment cAMP agonist (SpcAMP) completely blocked diminished insulin-stimulated protein. likely identity band regulatory confirmed assay immunoprecipitates competition studies peptide made. From these studies, conclude activates L6 increasing its subunit.
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