Myosin Phosphatase Rho Interacting Protein (MPRIP)

The deduced 1,024-amino acid protein has a calculated molecular mass of 116.4 kD. It has 2 proline-rich sequences near the N-terminus that are predicted to bind SH3 domains, a central pleckstrin homology (PH) domain, and a C-terminal coiled-coil region, which overlaps with the RhoA-binding domain.It also has sites for myristoylation and phosphorylation, and it has a putative nuclear localization signal. Immunohistochemical analysis of coronary artery smooth muscle cells showed that MRIP colocalized with MBS and RhoA at actin stress fibers. MRIP did not show nuclear localization. Western blot analysis detected endogenous MRIP at an apparent molecular mass of 125 kD in human smooth muscle cell lines.