Phosphatase Subfamily MTMR9
MTMR9 is a conserved pseudophosphatase across holozoan. It regulates active phosphatases of subfamily MTMR6.
MTMR9 is found throughout holozoan. It is usually single copy per genome.
MTMR9 subfamily has three domains: PH/GRAM, phosphatase domain and coiled-coil domain. The GRAM domain is similar to PH domain in structure and is found in membrane-associated proteins. As shown in MTMR3 subfamily, PH/GRAM domain can bind to phosphoinositide lipids. Coiled-coil domain has been shown to mediate the interaction between MTMR9 and members of MTMR6 in human [1, 2, 3].
Catalytic activity and functions
MTMR9 is an inactive phosphatase (pseudophosphatase). MTMR9 binds to phosphatases of MTMR6 subfamily: MTMR6 , MTMR7 , MTMR8 . The interactions increase the enzymatic activity of these phosphatases. The interaction between MTMR9 and members of MTMR6 subfamily is also observed in C. elegans .
- Mochizuki Y and Majerus PW. Characterization of myotubularin-related protein 7 and its binding partner, myotubularin-related protein 9. Proc Natl Acad Sci U S A. 2003 Aug 19;100(17):9768-73. DOI:10.1073/pnas.1333958100 |
- Zou J, Chang SC, Marjanovic J, and Majerus PW. MTMR9 increases MTMR6 enzyme activity, stability, and role in apoptosis. J Biol Chem. 2009 Jan 23;284(4):2064-71. DOI:10.1074/jbc.M804292200 |
- Zou J, Zhang C, Marjanovic J, Kisseleva MV, Majerus PW, and Wilson MP. Myotubularin-related protein (MTMR) 9 determines the enzymatic activity, substrate specificity, and role in autophagy of MTMR8. Proc Natl Acad Sci U S A. 2012 Jun 12;109(24):9539-44. DOI:10.1073/pnas.1207021109 |
- Silhankova M, Port F, Harterink M, Basler K, and Korswagen HC. Wnt signalling requires MTM-6 and MTM-9 myotubularin lipid-phosphatase function in Wnt-producing cells. EMBO J. 2010 Dec 15;29(24):4094-105. DOI:10.1038/emboj.2010.278 |