Identification and Characterization of Phostensin, a Novel Protein Phosphatase 1 F-actin Cytoskeleton Targeting Subunit

• Main Authors: Shu-Chen Kao, 高淑真
• Other Authors: 陳鴻震
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/57875407325778786174

博士 === 國立中興大學 === 生命科學系所 === 96 === Protein phosphatases 1（PP1）controls key biological pathways, including protein synthesis, carbohydrate metabolism, muscle contraction , cell cycle and neuron transmission via association with a variety of regulatory subunits that target the enzyme to various cellular locations. We have identified and characterized a novel protein, protein phosphatase 1 F-actin cytoskeleton targeting subunit (phostensin). This protein is encoded by KIAA1949 and was found to associate with PP1α in the co-immunoprecipitation, and GST pull-down assay. Phostensin is a protein of 165 amino acids with a calculated molecular mass of 17,771 and contains one consensus PP1-docking motif,K91ISF94. Mutation at the PP1-binding motif of phostensin disrupted binding with PP1. Imunofluorescence microscopic analysis revealed that the PP1α /phostensin complex was conspicuously localized with the actin cytoskeleton at the cell periphery in Madin-Darby canine kidney (MDCK) epithelial cells. The feature of phostensin that binds to the pointed ends of F-actin was observed in fluorescent actin polymerization assays using a FITC-conjugated monoclonalantibody, PT2.Phostensin binds to F-actin, and reduces F-actin elongation.Taken together, our results suggested that phostensin is an actin filament pointed end-capping protein and is capable of modulating actin dynamics.