Isolation of cDNA clones encoding protein kinase C: Evidence for a protein kinase C-related gene family

We have isolated cDNA clones encoding protein kinase C by using a 53-base-pair synthetic oligonucleotide probe corresponding to a peptide that we obtained from the rat brain enzyme. We also have isolated several closely related clones using the same oligonucleotide probe. Nucleotide sequence analysis of one of the protein kinase C clones, RP41, identifies a 224-aminoacid carboxyl-terminal region with ~40% homology to the carboxyl-terminal catalytic domains of both the cAMP-dependent and cGMP-dependent protein kinases. The levels of mRNA homologous to RP41 are very high in brain, whereas much lower levels are present in heart and liver. Nucleotide sequence analysis of a second cDNA clone, RP16, identifies a deduced amino acid sequence that shares 65% homology with the corresponding region of the protein kinase C clone RP41. The levels of mRNA corresponding to RP16 are also high in rat brain, but the transcript sizes and tissue-specific expression patterns differ from those of RP41. These and additional results provide evidence that the gene encoding protein kinase C is a member of a novel serine/threonine protein kinase multigene family.