Protein kinase C (PKC) is a family of enzymes found throughout the body, with the greatest diversity and concentration in brain tissue. To understand further the differential role of PKC isozymes in brain, we have raised antibodies against four PKC isoforms--alpha, beta I, beta II and gamma--using specific amino acid sequences predicted from cDNA sequences. On Western blot of rat cerebellar homogenate, these antibodies stained a band of Mr 80,000, a known molecular mass for PKC, except for anti-PKC(beta II), which stained an additional minor Mr 90,000 band. On rat cerebellar sections, specific sets of cells were stained by each antibody. In the molecular layer, stellate and basket cells were stained with anti-PKC(alpha) but not with anti-PKC(beta I), -(beta II), or -(gamma). Anti-PKC (alpha) and anti-PKC(beta II) seemed to stain the Bergmann glial fibre. In the Purkinje cell layer, Purkinje cells were stained with anti-PKC[beta I) and -(gamma). Anti-PKC (alpha) and -(beta II) were negative. Interestingly, a few Purkinje cells were not stained with anti-PKC(gamma). In the granule cell layer, both granule and Golgi cells were stained with anti-PKC(beta I) and -(beta II) but not with anti-PKC(alpha) or -(gamma). Glial cells were stained with anti-PKC(beta II) but not with anti-PKC(alpha), -(beta I), or -(gamma). This study suggests a differential distribution of PKC isoforms in different cells, irrespective of their neurotransmitters. The presence of both positive and negative staining of Purkinje cells with anti-PKC(gamma) raised the possibility of their heterogeneity.