Abstract
Analysis of membranes from a variety of tissues has revealed a widespread distribution of a protein phosphorylation system dependent on the presence of both Ca2+ and calcium-dependent regulator (CDR). This protein phosphorylation system has been studied in some detail in nervous tissue. Neuronal membranes contain a protein phosphorylation system that requires Ca2+ and a soluble heat-stable protein [Schulman, and Greengard, (1978)]. This protein was purified to homogeneity from bovine cerebral cortex, with use of an assay based on its ability to stimulate Ca2+-dependent protein phosphorylation in [rat cerebral cortex] membranes. This protein kinase activator appears to be identical to CDR of cyclic nucleotide phosphodiesterase. Throughout its purification, this single entity activated both Ca2+-dependent protein kinase and cyclic nucleotide phosphodiesterase. The kinase activator purified here and authentic CDR were equally effective in their ability to activate Ca2+-dependent protein kinase.

This publication has 22 references indexed in Scilit: