Sac phosphatase domain

Introduction

Domain of ~ 400 residues in length with ~ 35% identity among members. The Sac domain exhibits phosphatidylinositol polyphosphate phosphatase activity. It may hydrolyse phosphate from any of the 3 positions of inositol that may be phosphorylated (3-, 4- & 5). Adjacent phosphates are resistant. Sac domains cannot hydrolyse phosphate from PtdIns(4,5)P2), or PtdIns(3,4)P2 or PtdIns(3,4,5)P3, but can hydrolyse PtdIns(3,5)P2.

The Sac domain consists of 7 highly conserved motifs. The 6th conserved region contains a highly conserved C-x(5)-R-[TS] motif, thought to be the catalytic motif of many metal-independent protein & inositide polyphosphate phosphatases.

More general terms

• peptide motif
• domain