Protein and molecular characterization of hippocampal protein kinase C in C57BL/6 and DBA/2 mice

Measures of protein kinase C (PKC) in C57BL/6 and DBA/2 mice using [3H]phorbol 12,13-dibutyrate binding to tissue homogenates and brain slices demonstrated that levels of activated, membrane-bound PKC were greater in C57BL hippocampus than in DBA hippocampus. Western analysis of alpha-, beta I-, beta II-, gamma-, delta-, and epsilon-PKC using isozyme-specific antibodies indicated that the increase observed in C57BL hippocampus was due primarily to the gamma-PKC protein, whose immunoreactivity was greater in the membrane-bound fraction in C57BL mice. Characterization of alpha-, beta I,II-, and gamma-PKC hippocampal mRNA using northern analysis and isozyme-specific nucleic acid probes did not reveal differences between the strains in levels of gene expression. Restriction fragment length polymorphisms (RFLP) were found in the alpha- and gamma-, but not beta-PKC genomic DNA. The RFLPs appeared to be located in noncoding, nonregulatory regions of the gene. These findings suggest that the gamma-PKC isozyme is largely responsible for the PKC activity difference in C57BL and DBA hippocampus that has been reported previously and may be closely associated with differences in learning ability observed in these strains.