SIGNALING PROPERTIES OF GLYCOSYLPHOSPHATIDYLINOSITOLS AND THEIR REGULATED RELEASE FROM MEMBRANES IN THE TURNOVER OF GLYCOSYLPHOSPHATIDYLINOSITOL-ANCHORED PROTEINS

Glycosylphosphatidylinositols are involved in transmembrane signalling , and their signal mediated release from the cell membrane has been de monstrated for several hormones and growth factors. Presently, however , only indirect evidence exists for the enzyme responsible for the sig nal mediated release of glycosylphosphatidylinositols. Indirect eviden ce from product identification led to the conclusion that in mammals t he hormone sensitive activity is that of a glycosylphosphatidylinosito l anchor hydrolyzing phospholipase C. On the other hand a mammalian gl ycosylphosphatidylinositol anchor hydrolyzing phospholipase D is well- established. This enzyme most likely functions in the intracellular tu rnover of glycosylphosphatidylinositols, however, its possible relatio n to the signalling properties of glycosylphosphatidylinositols remain s unclear.