Myosin phosphatase group | Department of Medical Chemistry

Our research group studies the regulatory role of protein phosphorylation and dephosphorylation in cellular processes. Our major interest is the structure, localization and regulation of serine-threonine specific protein phosphatases type 1 (PP1) and type 2A (PP2A). The cellular functions of these enzymes are probed with cell-permeable phosphatase inhibitory toxins (okadaic acid, calyculin A, cantaridin and its derivatives). Type and subunit specific antibodies are applied for localization of these proteins in subcellular fractions by Western blots or by florescent microscopy. For the last few years our studies have focused on the role of protein-protein interactions in the mediation of activity of protein phosphatases including association of the catalytic subunits with regulatory subunits and inhibitory proteins. The methods applied include measurements of protein-protein interactions in real time with surface plasmon resonance technique (Biacore), immunological methods (FarWestern analysis) and other biochemical techniques (pull-down assays based on affinity chromatography, gel-filtration, etc.). To these assays we have expressed and purified recombinant catalytic and regulatory subunits and generated truncated as well as site-directed mutants to identify the regions and residues involved in the interactions and regulation.  Phosphatase activity may be controlled by phosphorylation of the regulatory and inhibitory proteins; therefore one of our major interests is to identify protein kinases that catalyze phosphorylation of the phosphatase-associating proteins and to dissect the signaling pathways involved in these regulatory processes. The above studies are carried out in collaboration with research groups at the University of Arizona (USA), Mie University School of Medicine (Japan) and the University of Calgary (Canada).