SET Binding Factor 2 (SBF2)

The family of myotubularin-related proteins includes lipid phosphatases, such as MTM1, and pseudophosphatases, such as SBF1 and SBF2. Pseudophosphatases contain inactivating substitutions at the catalytic cysteine.

The deduced 1,849-amino acid protein contains 3 N-terminal DENN domains, a central GRAM (glucosyltransferase, Rab-like GTPase activators, myotubularins) motif, a phosphatase domain, a SID (SET-interacting) domain, and a C-terminal pleckstrin homology (PH) motif. A leucine residue replaces the catalytic cysteine conserved in other myotubularins, indicating that SBF2 is a pseudophosphatase. SBF2 shares 36% sequence identity over 236 amino acids with MTMR2, and 59% overall sequence identity with SBF1.