A PTEN-like phosphatase with a novel substrate specificity.
We show that a novel PTEN-like phosphatase (PLIP) exhibits a unique preference for phosphatidylinositol 5-phosphate (PI(5)P) as a substrate in vitro. PI(5)P is the least characterized member of the phosphoinositide (PI) family of lipid signaling molecules. Recent studies suggest a role for PI(5)P in a variety of cellular events, such as tumor suppression, and in response to bacterial invasion. Determining the means by which PI(5)P levels are regulated is therefore key to understanding these cellular processes. PLIP is highly enriched in testis tissue and, similar to other PI phosphatases, exhibits poor activity against several proteinaceous substrates. Despite a recent report suggesting a role for PI(5)P in the regulation of Akt, the overexpression of wild-type or catalytically inactive PLIP in Chinese hamster ovary-insulin receptor cells or a dsRNA-mediated knockdown of PLIP mRNA levels in Drosophila S2 cells does not alter Akt activity or phosphorylation. The unique in vitro catalytic activity and detailed biochemical and kinetic analyses reported here will be of great value in our continued efforts to identify in vivo substrate(s) for this highly conserved phosphatase.
Pagliarini
David J
DJ
Department of Pharmacology, University of California, San Diego, La Jolla, California 92093-0721, USA.
Worby
Carolyn A
CA
Dixon
Jack E
JE
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015152:Blotting, Northern; D001896:Boron Compounds / Q000494:pharmacology; D016466:CHO Cells; D002384:Catalysis; D002460:Cell Line; D002855:Chromatography, Thin Layer; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004330:Drosophila; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008055:Lipids / Q000737:chemistry; D008297:Male; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D051059:PTEN Phosphohydrolase; D010716:Phosphatidylinositols / Q000737:chemistry; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000737:chemistry; D011972:Receptor, Insulin / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012394:Rosaniline Dyes / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013379:Substrate Specificity; D013737:Testis / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000502:physiology*; D017027:Protein Tyrosine Phosphatases
D001896:Boron Compounds; D005982:Glutathione Transferase; D008055:Lipids; D051059:PTEN Phosphohydrolase; D010716:Phosphatidylinositols; D010744:Phosphoric Monoester Hydrolases; D012330:RNA, Double-Stranded; D011972:Receptor, Insulin; D011994:Recombinant Proteins; D012394:Rosaniline Dyes; D025521:Tumor Suppressor Proteins; C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; C005095:malachite green; C492433:Ptpmt1 protein, mouse; D017027:Protein Tyrosine Phosphatases; C494929:PTEN protein, human