THE SH2 DOMAIN-CONTAINING INOSITOL 5-PHOSPHATASE SHIP2 DISPLAYS PHOSPHATIDYLINOSITOL 3,4,5-TRISPHOSPHATE AND INOSITOL 1,3,4,5-TETRAKISPHOSPHATE 5-PHOSPHATASE ACTIVITY

Distinct forms of inositol and phosphatidylinositol polyphosphate 5-ph osphatases selectively remove the phosphate from the 5-position of the inositol ring from both soluble and lipid substrates, SHIP1 is the 14 5-kDa SH2 domain-containing inositol 5-phosphatase expressed in haemat opoietic cells, SHIP2 is a related but distinct gene product. We repor t here that SHIP2 can be expressed in an active form both in Escherich ia coli and in COS-7 cells, A truncated 103-kDa recombinant protein co uld be purified from bacteria that display both inositol 1,3,4,5-tetra kisphosphate (InsP(4)) and phosphatidylinositol 3,4,5-trisphosphate (P tdIns(3,4,5)P-3) phosphatase activities. COS-7 cell lysates transfecte d with SHIP2 had increased PtdIns(3,4,5)P-3 phosphatase activity as co mpared to the vector alone. (C) 1998 Federation of European Biochemica l Societies.