Small G Protein Signaling Modulator 3 (SGSM3)

RUTBC3 binds merlin and that the interaction is mediated by the RUTBC3 RUN domain and the C-terminal region of merlin. By confocal microscopy of RUTBC3 and merlin expressed in NIH3T3 cells, the authors found that RUTBC3 localized to perinuclear and membrane regions and merlin localized to the cytoplasmic membrane. When RUTBC3 was coexpressed with merlin, RUTBC3 and merlin colocalized to the cytoplasmic membrane. The deduced 749-amino acid protein has a predicted molecular mass of 84.5 kD, confirmed by in vitro translation. RUTBC3 contains an N-terminal TBC domain, a central SH3 domain, and a C-terminal RUN domain. RUTBC3 increased merlin-mediated repression of AP1-dependent promoter activity in a dose-dependent manner.