Merida I, Mato JM. Inhibition by insulin of glucagon-dependent phospholipid methyltransferase phosphorylation in rat hepatocytes.
BIOCHIMICA ET BIOPHYSICA ACTA 1987;
928:92-7. [PMID:
3548831 DOI:
10.1016/0167-4889(87)90089-9]
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Abstract
Addition of insulin to isolated rat hepatocytes prelabeled with [32P]phosphate inhibited glucagon-dependent phospholipid methyltransferase phosphorylation and activation. Insulin alone had no effect on either the phosphorylation of the enzyme or on its activity. The effect of insulin on glucagon-dependent phospholipid methyltransferase phosphorylation was dose-dependent and occurred at physiological doses of the hormone (10(-11)-10(-10) M). Analysis of 32P-labeled peptides after digestion with trypsin revealed only one site of phosphorylation regulated by glucagon (10(-8) M) in isolated rat hepatocytes. This site, as analyzed by HPLC and thin-layer chromatography, coincided with that phosphorylated by the cAMP-dependent protein kinase using purified rat liver phospholipid methyltransferase.
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