|PROSITE documentation PDOC51339
Myotubularin phosphatase domain
Myotubularin phosphatases are members of the protein tyrosine phosphatase
(PTP) superfamily. The PTP domain is found in a diverse group of enzymes that
catalyze phosphoester hydrolysis using a cysteine nucleophile and an arginine
residue that binds to oxygen atoms of the phosphate. These two catalytically
essential residues are found in a Cys-x(5)-Arg motif, which is a hallmark of
PTP domains (see <PDOC00323>). The PTP superfamily of enzymes includes
tyrosine-specific, dual specificity, low molecular weight, and Cdc25
phosphatases. All of these enzymes utilize phosphoproteins as substrates.
Unlike these members of PTPs, enzymes that contain the tensin (see
<PDOC51181>) and myotubularin PTP domain utilize the phosphoinositide as its
physiologic substrate. Myotubularins are 3-phosphatases specific for
membrane-embedded PtdIns3P and PtdIns(3,5)P2, two PIs that function within the
endosomal-lysosomal pathway [1,2].
The myotubularin phosphatase domain consists of a central seven stranded β
sheet flanked by thirteen α helices (see <PDB:1LW3>) . Although its
core structure is similar to that of other PTP superfamily members, the
myotubularin phosphatase domain is much larger. It contains an extra
C-terminal region, which could be implicated in protein-protein interactions.
The active site motif forms a P-loop at the base of a substrate binding pocket
that is characteristic of PTP domains. This pocket is significantly deeper
than that of other PTP pockets, which could explain the difference in
The profile we developed covers the whole myotubularin phosphatase domain.
November 2007 / First entry.
PROSITE method (with tools and information) covered by this documentation:
|PPASE_MYOTUBULARIN, PS51339; Myotubularin phosphatase domain (MATRIX)
|Sequences known to belong to this class detected by the profile:
|Other sequence(s) detected in Swiss-Prot:
|Matching PDB structures:
1LW3 1M7R 1ZSQ 1ZVR ... [ALL]
||Denu J.M., Dixon J.E.
||Protein tyrosine phosphatases: mechanisms of catalysis and regulation.
||Curr. Opin. Chem. Biol. 2:633-641(1998).
||Robinson F.L., Dixon J.E.
||Myotubularin phosphatases: policing 3-phosphoinositides.
||Trends Cell Biol. 16:403-412(2006).
||Begley M.J., Taylor G.S., Kim S.A., Veine D.M., Dixon J.E., Stuckey J.A.
||Crystal structure of a phosphoinositide phosphatase, MTMR2: insights into myotubular myopathy and Charcot-Marie-Tooth syndrome.
||Mol. Cell 12:1391-1402(2003).
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