Identification and characterization of a sac domain-containing phosphoinositide 5-phosphatase.
We have characterized a novel Sac domain-containing inositol phosphatase, hSac2. It was ubiquitously expressed but especially abundant in the brain, heart, skeletal muscle, and kidney. Unlike other Sac domain-containing proteins, hSac2 protein exhibited 5-phosphatase activity specific for phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. This is the first time that the Sac domain has been reported to possess 5-phosphatase activity. Its 5-phosphatase activity for phosphatidylinositol 4,5-bisphosphate (K(m) = 14.3 microm) was comparable with those of Type II 5-phosphatases. These results imply that hSac2 functions as an inositol polyphosphate 5-phosphatase.
Department of Biochemistry, The Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639 Japan.
T
T
Minagawa
T
T
Ijuin
Y
Y
Mochizuki
T
T
Takenawa
D000595:Amino Acid Sequence; D001483:Base Sequence; D018076:DNA, Complementary; D006801:Humans; D000072181:Inositol Polyphosphate 5-Phosphatases; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D010716:Phosphatidylinositols; D011994:Recombinant Proteins; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases; C000606431:INPP5F protein, human; D000072181:Inositol Polyphosphate 5-Phosphatases