CLONING AND EXPRESSION OF A HUMAN PLACENTA INOSITOL 1,3,4,5-TETRAKISPHOSPHATE AND PHOSPHATIDYLINOSITOL 3,4,5-TRISPHOSPHATE 5-PHOSPHATASE

Distinct inositol and phosphatidylinositol polyphosphate 5-phosphatase s have recently been cloned. Primers were designated coding for highly conserved amino acid regions that are shared between sequences of 5-p hosphatases. We used degenerate primers to amplify polymerase chain re action products from rat brain cDNA. A product with a novel sequence w as identified and used to clone a 4.9 kb cDNA from human placenta cDNA libraries (hp51CN). COS-7 cells transfected with a C-terminal truncat ed form of this cDNA showed an increase in Ins(1,3,4,5)P-4 and PtdIns( 3,4,5)P-3 hydrolyzing activity, but not in Ins(1,4,5)P-3 5-phosphatase . Enzymatic activity was inhibited in the presence of 2,3-bisphosphogl ycerate and p-hydroxymercuribenzoate. The presence of an SH2 domain an d proline-rich sequence motifs within hp51CN suggests that this 5-phos phatase interacts with various proteins in signal transduction. (C) 19 96 Academic Press, Inc.