Stimulation of the insulin-sensitive cAMP phosphodiesterase by an ATP-dependent soluble factor from insulin-treated rat adipocytes.

Abstract The insulin-sensitive cAMP phosphodiesterase (PDE) in the microsomal fraction (Fraction P-2) from basal (-insulin) rat adipocytes was stimulated upon incubation with 2 mM ATP plus the soluble fraction from insulin-treated adipocytes (Fraction S-2 + ). Fraction S-2 + was prepared in the presence of p-nitrophenylphosphate, sodium vanadate, and EGTA. The ATP-dependent stimulation of PDE was routinely 60–70%. The unknown factor in Fraction S-2 was water-soluble, heat-labile, excluded by Sephadex G-50, mostly retained by Sephadex G-100, and not inhibited with 1 μg/ml heparin, 3 mM CaCl 2 , or 30 mM NaF. The soluble factor may be a mediator of insulin action on PDE, possibly a protein kinase.