EFFECTS OF INSULIN ON THE TRANSLOCATION OF PROTEIN-KINASE C-THETA ANDOTHER PROTEIN-KINASE-C ISOFORMS IN RAT SKELETAL-MUSCLES

Protein kinase C (PKC)-theta is a newly recognized major PKC isoform i n skeletal muscle. In this study we found that insulin provoked rapid biphasic increases in membrane-associated immunoreactive PKC-theta as well as PKC-alpha, PKC-beta and PKC-epsilon, in rat soleus muscles inc ubated ill vitro. Effects of insulin on PKC isoforms in the soleus wer e comparable in magnitude with those of phorbol esters. Increases in m embrane-associated PKC-theta, PKC-alpha, PKC-beta and PKC-epsilon were also observed in rat gastrocnemius muscles after insulin treatment in vivo. Our findings suggest that PKC-theta, like other diacylglycerol- sensitive PKC isoforms (alpha, beta and epsilon), may play a role in i nsulin action in skeletal muscles.