Difference between revisions of "Phosphatase Family Myotubularin"

Revision as of 18:17, 31 December 2014

Phosphatase Classification: FoldCC1: Superfamily CC1: Family Myotubularin

Myotubularins are 3-phosphatases specific for PtdIns3P and PtdIns(3,5)P2, two PIs that function within the endosomal-lysomal pathway . In yeast, there is a single myotubularin Ymr1p, and its functions appear to be redundant with those of other 3-phosphatases. In C. elegans, which has six myotubularins, several of the myotublarins have non-redundant roles in regulating PtdIns3P during endocytosis. In human, there are 14 myotublarins, and mutations in several of them lead to myotubular myopathy and Charcot-Marie-Tooth peripheral neuropathy. Interestingly, around half of myotubularins are catalytically inactive. One of their possible function is regulating active myotubularins by protein interaction. For details, see the review [1].

Subfamilies

MTMR1

MTMR1 is a lipid phosphatase that dephosphorylates the second messenger phosphatidylinositol 3-monophosphate [PI(3)P]. It is found across holozoan.

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.

MTMR5 (SBF)

MTMR5 is a subfamily of inactive phosphatase (pseudophosphatase) conserved in metazoan. It regulates the active phosphatase MTMR2 by protein interactions.

MTMR6

MTMR9

MTMR9 is a conserved pseudophosphatase across holozoan. It regulates active phosphatases of subfamily MTMR6.

MTMR10

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.

YMR1

Yeast has a single myotubularin YMR1, encoding PI(3)P phosphatase [2].

Reference

1. 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 | PubMed ID:16828287 | HubMed [Robinson06]
2. 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 | PubMed ID:10900271 | HubMed [taylor00]