ABSTRACT
In this report, we identified the novel protein heart protein phosphatase 1-binding protein (Hepp1), encoded by FLJ23654. Hepp1 associated with protein phosphatase 1 (PP1) by yeast two-hybrid, GST pull-down, co-immunoprecipitation, and far Western blotting assays. Northern blot analysis revealed that Hepp1 mRNA was only expressed in human heart and testis. Recombinant Hepp1 slightly enhanced the enzymatic activity of PP1 and antagonized the ability of phospho-inhibitor-1 or inhibitor-2 to inhibit PP1. Hepp1 protein in human heart tissues was detected by Western blot analysis. Together, our data suggest that Hepp1 can play a role in cardiac functions by working in concert with PP1.
Subject(s)
Myocardium/metabolism , Protein Phosphatase 1/metabolism , Amino Acid Sequence , Animals , Carrier Proteins/genetics , Carrier Proteins/metabolism , Humans , Male , Molecular Sequence Data , Oncogene Proteins , Protein Phosphatase 1/antagonists & inhibitors , Rabbits , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Testis/metabolism , Two-Hybrid System Techniques , Ubiquitin-Protein LigasesABSTRACT
We have identified a novel protein, protein phosphatase 1 F-actin cytoskeleton targeting subunit (phostensin). This protein is encoded by KIAA1949 and was found to associate with protein phosphatase 1 (PP1) in the yeast two-hybrid assay, co-immunoprecipitation, and GST pull-down assay. Northern blot analysis revealed that phostensin mRNA was predominantly distributed in leukocytes and spleen, and phostensin protein was present in crude extracts of human peripheral leukocytes. Immunofluorescence microscopic analysis revealed that the phostensin/PP1 complex was conspicuously localized with the actin cytoskeleton at the cell periphery in Madin-Darby canine kidney (MDCK) epithelial cells. Taken together, our data shows that phostensin targets PP1 to F-actin cytoskeleton. The phostensin/PP1 complex may play a vital role in modulation of actin rearrangements.