Myosin phosphatase-rho interacting protein (M-RIP), also known as p116RIP, RIP3, and MPRIP, localizes to actin-myosin filaments regulating cytoskeletal dynamics. M-RIP contains amino-terminal pleckstrin homology domains, carboxyl-terminal coiled-coil domains, and was originally identified to associate with the myosin phosphatase complex. M-RIP binds to MBS/MYRT, the myosin binding subunit of myosin phosphatase, as well as RhoA. Phosphorylation of MYRT by Rho-associated kinase (ROCK) inhibits myosin phosphatase activity, resulting in increased levels of phosphorylation on myosin light chain, and enhanced contractility. M-RIP may function as a scaffolding protein for the complex between the myosin phosphatase complex, Rho/ROCK, and actin. Silencing of M-RIP results in disassembly of the complex, increased phosphorylation of myosin light chain, and changes to cytoskeletal dynamics.
