Characterization and Distribution of Protein Kinase C Isoforms in Human Skin Fibroblasts

In the present study we have examined the distribution of several isoforms of protein kinase C, a lipid-regulated serine/threonine kinase essential for signal transduction and cell regulation, in cultured human skin fibroblasts. By Western blot analysis we have detected the presence of at least three of the known protein kinase C isoforms. The calcium-dependent protein kinase Cα was primarily associated with the cytosolic fraction. Three non-calcium-dependent isoforms, protein kinases Cϵ, Cδ, and Cζ, were also detected. Protein kinases Cζ and Cδ were present primarily in the cytosol, while protein kinase Cϵ was associated primarily with the membrane fraction. Binding and activity studies were consistent with the pattern of expression and distribution defined by Western blot analysis. These results provide a useful frame of reference for the study of isoform-specific effects of protein kinase C in the regulation of cell growth and metabolism.