Existence d'une activité protéine kinase stimulable par le 3′,5′ — adénosine monophosphate cyclique dans le tissu adipeux d'un poisson téléostéen, la truite ( Salmo gairdnerii R.)

Abstract

Summary A cAMP sensitive protein kinase activity was demonstrated in the soluble extract of adipose tissue from a teleost fish, the rainbow trout ( Salmo gairdnerii ). Two enzymes with different K m (0.2 and 1.6.10 −6 M) for ATP were apparently present; cAMP doubled the total V max without extensive effects on the K m 's; the apparent K a of the enzymatic preparation for cAMP was 0.05 × 10 −6 M; cGMP was about 150 times less active than cAMP. Cyclic AMP and protein kinase metabolisms may therefore be targets for a possible hormonal regulation of the activity of fish adipose tissue. However no significant difference in adipose tissue protein kinase activity was observed between two groups of trouts which differed by the relative importance of the adipose deposits. Moreover theophylline, which does not increase lipolysis when incubated with teleost adipose tissue, clearly stimulated the protein kinase activity in a homogenate of this tissue.