Members of this family catalyse the hydrolysis of the 4-position phosphate of phosphatidylinositol 4,5-bisphosphate, in the reaction: 1-phosphatidyl-myo-inositol 4,5-bisphosphate + H(2)O = 1-phosphatidyl-1D-myo-inositol 5-phosphate + phosphate.

1: The identification and characterization of two phosphatidylinositol-4,5-bisphosphate 4-phosphatases. Ungewickell A, Hugge C, Kisseleva M, Chang SC, Zou J, Feng Y, Galyov EE, Wilson M, Majerus PW; Proc Natl Acad Sci U S A. 2005;102:18854-18859. PMID:16365287