PIPkins, their substrates and their products: new functions for old enzymes

The phosphatidylinositolphosphate kinases (PIPkins) are a unique family of enzymes that catalyse the production of phosphorylated inositol lipids. Rec ent advances have revealed that, due to their ability to utilise a number o f different lipid substrates (at least in vitro), this family is potentiall y able to generate several distinct, physiologically important inositol lip ids. Despite their importance, however, our understanding of the regulation of the PIPkins and of their physiological role in cellular signalling and regulation is still poor. Here we describe in turn the diverse physiologica l functions of the known substrates and major products of the PIPkins. We t hen examine what is known about the members of the PIPkin family themselves , and their characteristics and regulation. (C) 1998 Elsevier Science B.V. All rights reserved.