Cloning, and characterization of a 72-kDa inositol-polyphosphate 5-phosphatase localized to the Golgi network
- Author(s)
- Kong, AM; Speed, CJ; O'Malley, CJ; Layton, MJ; Meehan, T; Loveland, KL; Cheema, S; Ooms, LM; Mitchell, CA;
- Details
- Publication Year 2000-08-04,Volume 275,Issue #31,Page 24052-24064
- Journal Title
- JOURNAL OF BIOLOGICAL CHEMISTRY
- Publication Type
- Journal Article
- Abstract
- The inositol-polyphosphate B-phosphatase enzyme family removes the B-position phosphate from both inositol phosphate and phosphoinositide signaling molecules. We have cloned and characterized a novel B-phosphatase, which demonstrates a restricted substrate specificity and tissue expression. The 3.9-kb cDNA predicts for a 72-kDa protein with an N-terminal proline rich domain, a central B-phosphatase domain, and a C-terminal CAAX motif. The 3.9-kilobase mRNA showed a restricted expression but was abundant in testis and brain. Antibodies against the sequence detected a 72-kDa protein in the testis in the detergent-insoluble fraction. Indirect immunofluorescence of the Tera-1 cell line using anti-peptide antibodies to the 72-kDa 5-phosphatase demonstrated that the enzyme is predominantly located to the Golgi. Expression of green fluorescent protein-tagged 72-kDa 5-phosphatase in COS-7 cells revealed that the enzyme localized predominantly to the Golgi, mediated by the N-terminal proline-rich domain, but not the C-terminal CAAX motif. In vitro, the protein inserted into microsomal membranes on the cytoplasmic face of the membrane. Immunoprecipitated recombinant 72-kDa B-phosphatase hydrolyzed phosphatidylinositol 3,4,5-trisphosphate and phosphatidylinositol 3,5-bisphosphate, forming phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol S-phosphate, respectively. We propose that the novel 5-phosphatase hydrolyzes phosphatidylinositol 3,4,5-trisphosphate and phosphatidylinositol 3,5-bisphosphate on the cytoplasmic Golgi membrane and thereby may regulate Golgi-vesicular trafficking.
- Publisher
- AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
- Keywords
- PRENYLCYSTEINE CARBOXYL METHYLTRANSFERASE; ENDOPLASMIC-RETICULUM MEMBRANE; GUANINE-NUCLEOTIDE EXCHANGE; PHOSPHATIDYLINOSITOL 3,4,5-TRISPHOSPHATE; HUMAN-PLATELETS; SACCHAROMYCES-CEREVISIAE; PROTEIN; IDENTIFICATION; 3-KINASE; POLYPHOSPHATE-5-PHOSPHATASE
- Publisher's Version
- https://doi.org/10.1074/jbc.M000874200
- Open Access at Publisher's Site
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Creation Date: 2000-08-04 12:00:00