Difference between revisions of "Phosphatase Subfamily MTMR1"

Revision as of 00:10, 31 December 2014

Phosphatase Classification: FoldCC1: Superfamily CC1: Family Myotubularin: Subfamily MTMR1

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

Evolution

MTMR1 is found throughout holozoan. It consists of three members in human, MTM1, MTMR1 and MTMR2. In fruit fly and C elegans, a single copy is found. In most vertebrates from bony fish to human, MTM1 and MTMR1 are adjacent on the X chromosome (see Genomicus).

Domain Structure

MTMR1 subfamily has a 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 MTMR subfamily, PH/GRAM domain can bind to phosphoinositide lipids. In Monosiga, the GRAM is replaced by a C1 domain, which is also a lipid-binding domain. Coiled-coil domain has been shown to mediate the interaction between MTMR2 and MTMR5 and between MTMR2 and MTMR13 in human [1, 2]. MTMR5 belongs to MTMR5 subfamily.

Catalytic activity and functions

Human MTM1 has phosphatase activity towards the second messenger phosphatidylinositol 3-monophosphate [PI(3)P] in vitro and in human, budding yeast, and fission yeast [3, 4]. Human MTMR1 and MTMR2 have been shown to dephosphorylate PI(3)P ([5] and [6], respectively). Although the enzymatic properties of the three human phosphatases are indistinguishable, their functions are not totally redundant. MTM1 and MTMR2 are differentially regulated in the aspects of developmental expression and subcellular localization, resulting in their use of specific cellular pools of PI(3)P [6].

Related Kinases

See PI3K.

References

1. Kim SA, Vacratsis PO, Firestein R, Cleary ML, and Dixon JE. Regulation of myotubularin-related (MTMR)2 phosphatidylinositol phosphatase by MTMR5, a catalytically inactive phosphatase. Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4492-7. DOI:10.1073/pnas.0431052100 | PubMed ID:12668758 | HubMed [kim03]
2. Robinson FL and Dixon JE. The phosphoinositide-3-phosphatase MTMR2 associates with MTMR13, a membrane-associated pseudophosphatase also mutated in type 4B Charcot-Marie-Tooth disease. J Biol Chem. 2005 Sep 9;280(36):31699-707. DOI:10.1074/jbc.M505159200 | PubMed ID:15998640 | HubMed [robinson05]
3. 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]
4. Blondeau F, Laporte J, Bodin S, Superti-Furga G, Payrastre B, and Mandel JL. Myotubularin, a phosphatase deficient in myotubular myopathy, acts on phosphatidylinositol 3-kinase and phosphatidylinositol 3-phosphate pathway. Hum Mol Genet. 2000 Sep 22;9(15):2223-9. DOI:10.1093/oxfordjournals.hmg.a018913 | PubMed ID:11001925 | HubMed [blondeau00]
6. Kim SA, Taylor GS, Torgersen KM, and Dixon JE. Myotubularin and MTMR2, phosphatidylinositol 3-phosphatases mutated in myotubular myopathy and type 4B Charcot-Marie-Tooth disease. J Biol Chem. 2002 Feb 8;277(6):4526-31. DOI:10.1074/jbc.M111087200 | PubMed ID:11733541 | HubMed [kim01]
7. Buj-Bello A, Furling D, Tronchère H, Laporte J, Lerouge T, Butler-Browne GS, and Mandel JL. Muscle-specific alternative splicing of myotubularin-related 1 gene is impaired in DM1 muscle cells. Hum Mol Genet. 2002 Sep 15;11(19):2297-307. DOI:10.1093/hmg/11.19.2297 | PubMed ID:12217958 | HubMed [bujbell02]