Amgen Institute, Toronto, Ontario, Canada.
The action of lipid phosphatases on inositol phosphates is thought to be one method that the cell uses to attenuate growth factor- or cytokine-induced mobilization of calcium. We have cloned a cDNA from a mouse spleen library that is virtually identical to the recently described inositol tetraphosphate and phosphatidylinositol 3,4,5-trisphosphate 5-phosphatase, SHIP. Chromosomal localization studies in human and mouse by FISH mapping and interspecies backcrossing in mice have demonstrated that human SHIP is localized to 2q36-q37.1 and that mouse SHIP is localized to 1C5.