Myotubularian (MTM) related 11 protein (MTMR11) Pleckstrin Homology-Glucosyltransferases, Rab-like GTPase activators and Myotubularins (PH-GRAM) domain
MTMR10, MTMR11, and MTMR12 are catalytically inactive phosphatases that play a role as an adapter for the phosphatase myotubularin to regulate myotubularintracellular location. They contains a Glu residue instead of a conserved Cys residue in the dsPTPase catalytic loop which renders it catalytically inactive as a phosphatase. They contains an N-terminal PH-GRAM domain, a Rac-induced recruitment domain (RID) domain, an inactive PTP domain, a SET interaction domain, and a C-terminal coiled-coil domain. Myotubularin-related proteins are a subfamily of protein tyrosine phosphatases (PTPs) that dephosphorylate D3-phosphorylated inositol lipids. Mutations in this family cause the human neuromuscular disorders myotubular myopathy and type 4B Charcot-Marie-Tooth syndrome. 6 of the 13 MTMRs (MTMRs 5, 9-13) contain naturally occurring substitutions of residues required for catalysis by PTP family enzymes. Although these proteins are predicted to be enzymatically inactive, they are thought to function as antagonists of endogenous phosphatase activity or interaction modules. Most MTMRs contain a N-terminal PH-GRAM domain, a Rac-induced recruitment domain (RID) domain, a PTP domain (which may be active or inactive), a SET-interaction domain, and a C-terminal coiled-coil region. In addition some members contain DENN domain N-terminal to the PH-GRAM domain and FYVE, PDZ, and PH domains C-terminal to the coiled-coil region. The GRAM domain, found in myotubularins, glucosyltransferases, and other putative membrane-associated proteins, is part of a larger motif with a pleckstrin homology (PH) domain fold.