The regulation of KIF3 motor complex by POPX2 phosphatase

Abstract

The POPX2 serine/threonine phosphatase was first identified as a Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKPase). Later, the phosphatase was isolated as a binding partner of PIX, a guanine nucleotide exchange factor of the Rho GTPases. POPX2 has been shown to dephosphorylate and downregulate the activity of the Cdc42/Rac1-activated kinase, PAK1, through formation of POPX2-PIX-PAK1 trimeric complex. Recent studies have also demonstrated that POPX2 interacts with the mammalian Diaphanous (mDia) protein and this interaction reduced the ability of mDia to activate transcription mediated by the serum response factor (SRF). Furthermore, POPX2 has also been implicated in the regulation of breast cancer cell motility and invasiveness.