Phosphatase Family Myotubularin
Phosphatase Classification: FoldCC1: Superfamily CC1: Family Myotubularin
Myotubularins are phosphoinositide phosphatase found in a broad of eukaryotes. Human genome has 15 myotubularins and 7 subfamilies. Generally, human myotubularins are dephosphorylating phosphatidylinositol 3-phosphate [PtdIns(3)P] and phosphatidylinositol 3,5-bisphosphate [PtdIns (3,5)P2], but they are not redundant and have unique functions within cells by regulating a specific pool of PI(3)P or PI(3,5)P2 [1]. For example, subcellular localization of MTMR6 is regulated by interaction with small GTPase via its PH/GRAM domain. Another feature of myotubularins is pseudophosphatases within the family. 6 out of 15 human myotubularins are catalytically inactive. Their major functions are regulating the enzymatic activity of active myotubularins, e.g. the pairs between MTMR1:MTMR5, MTMR6:MTMR9.
Contents
[hide]Subfamilies
MTMR1
MTMR1 is a lipid phosphatase that dephosphorylates the second messenger phosphatidylinositol 3-monophosphate [PI(3)P]. It is found across holozoan.
MTMR5 (SBF)
MTMR5 is a subfamily of pseudophosphatase conserved in metazoan. It regulates the active MTMR1 subfamily by protein interactions.
MTMR6
MTMR6 is a phosphoinositide phosphatase found in holozoan. Its enzymatic activity is regulated by MTMR9.
MTMR9
MTMR9 is a conserved pseudophosphatase across holozoan. It regulates active phosphatases of subfamily MTMR6.
MTMR3
MTMR3 is an inositol lipid 3-phosphatase. It is probably a protein phosphatase of receptor-regulated SMAD. It is found throughout metazoan, with a signature FYVE domain.
MTMR14
MTMR14 is an active phosphatase found in most holozoan and slime molds. Its putative substrates are phosphatidylinositol bisphophosphates PtdIns(3,5)P2 and PtdIns (3,4)P2.
MTMR10
YMR1
Yeast has a single myotubularin YMR1, encoding PI(3)P phosphatase [2].
Reference
- Robinson FL and Dixon JE. Myotubularin phosphatases: policing 3-phosphoinositides. Trends Cell Biol. 2006 Aug;16(8):403-12. DOI:10.1016/j.tcb.2006.06.001 |
- Taylor GS, Maehama T, and Dixon JE. Myotubularin, a protein tyrosine phosphatase mutated in myotubular myopathy, dephosphorylates the lipid second messenger, phosphatidylinositol 3-phosphate. Proc Natl Acad Sci U S A. 2000 Aug 1;97(16):8910-5. DOI:10.1073/pnas.160255697 |