Sac phosphatase domain proteins

Advances in our understanding of the roles of phosphatidylinositol phosphat es in controlling cellular functions such as endocytosis, exocytosis and th e actin cytoskeleton have included new insights into the phosphatases that are responsible for the interconversion of these lipids, One of these is an entirely novel class of phosphatase domain found in a number of well chara cterized proteins. Proteins containing this Sac phosphatase domain include the yeast Saccharomyces cerevisiae proteins Sac1p and Fig4p, The Sac phosph atase domain is also found within the mammalian phosphoinositide 5-phosphat ase synaptojanin and the yeast synaptojanin homologues Inp51p, Inp52p and I np53p. These proteins therefore contain both Sao phosphatase and 5-phosphat ase domains. This review describes the Sac phosphatase domain-containing pr oteins and their actions, with particular reference to the genetic and bioc hemical insights provided by study of the yeast Saccharomyces cerevisiae.