Characterization of myotubularin-related protein 7 and its binding partner, myotubularin-related protein 9.

Myotubularin-related protein 7 (MTMR7) is a member of the myotubularin (MTM) family. The cDNA encoding the mouse MTMR7 contains 1,983 bp, and the predicted protein has a deduced molecular mass of 75.6 kDa. Northern and Western blot analyses showed that MTMR7 is expressed mainly in brain and mouse neuroblastoma N1E-115 ...
cells. Recombinant MTMR7 dephosphorylated the D-3 position of phosphatidylinositol 3-phosphate and inositol 1,3-bisphosphate [Ins(1,3)P2]. The substrate specificity of MTMR7 is different than other MTM proteins in that this enzyme prefers the water-soluble substrate. Immunofluorescence showed that MTMR7 is localized in Golgi-like granules and cytosol, and subcellular fractionation showed both cytoplasmic and membrane localization of MTMR7 in N1E-115 cells. An MTMR7-binding protein was found in an anti-MTMR7 immunoprecipitate from N1E-115 cells and identified as MTM-related protein 9 (MTMR9) by tandem mass spectrometry. The coiled-coil domain of MTMR9 was sufficient for binding to MTMR7. The binding of MTMR9 increased the Ins(1,3)P2 phosphatase activity of MTMR7. Our results show that MTMR7 forms a complex with MTMR9 and dephosphorylates phosphatidylinositol 3-phosphate and Ins(1,3)P2 in neuronal cells.
Mesh Terms:
Amino Acid Sequence, Animals, Binding Sites, Brain, COS Cells, Carrier Proteins, Cell Line, DNA, Complementary, Humans, Inositol Phosphates, Mice, Molecular Sequence Data, Phosphatidylinositol Phosphates, Phosphoric Monoester Hydrolases, Protein Binding, Protein Structure, Tertiary, Protein Tyrosine Phosphatases, Protein Tyrosine Phosphatases, Non-Receptor, Recombinant Proteins, Substrate Specificity, Tissue Distribution
Proc. Natl. Acad. Sci. U.S.A.
Date: Aug. 19, 2003
Download Curated Data For This Publication
12750
Switch View:
  • Interactions 8