The Role of Protein Kinase C in Transmembrane Signalling

Inositol phospholipids have attracted great attention from researchers studying the activation of cellular functions and proliferation. In the action of a group of hormones, neurotransmitters, or other biologically active substances, including some growth factors, a signal-induced degradation of the phospholipids may generate important intracellular second messengers that function differently from cyclic AMP. The response of inositol phospholipids to the activation of cell surface receptors was first recognized by Hokin & Hokin ( 1953), who showed with pancreatic slices that ace­ tylcholine induces a rapid incorporation of 32p into phosphatidylinositol (PI) and phosphatidic acid. It later became evident that breakdown and resynthesis of inositol phospholipids occur in many cell types in response