Inositol 1,3,4,5-tetrakisphosphate as a second messenger - a special role in neurones?

There has been much controversy over the possibility that inositol 1,3,4,5- tetrakisphosphate (InsP(4)) may have a second messenger function. A possibl e resolution to this controversy may stem from the recent cloning of two pu tative receptors for InsP(4), GAP1(IP4BP) and GAP1m. Both these proteins ar e expressed at high levels in neurones, as is inositol 1,4,5-trisphosphate 3-kinase, the enzyme that makes InsP(4). In this review we discuss the poss ible relevance of these high expression levels to the complex way in which neurones control Ca2+ and use it as a second messenger. (C) 1999 Elsevier S cience Ireland Ltd. All rights reserved.