Immunolocalization of PKCξ in rat photoreceptor inner segments

We have utilized several peptide specific antisera directed against the C-terminals (Wetsel et al, 1992) of several protein kinase C (PKC) isozymes (α β₁, β₁₁, γ δ ε ξ to delineate the cellular localization of these PKC isozymes in rat retina. Antisera against PKC β₁, β₁₁, γ δ and ε were non-reactive in frozen rat retina sections, whereas, anti PKCα was strongly reactive with the outer plexiform, inner plexiform and nerve fiber cell layers. The most specific localization of immunoreactivity was observed with PKCξ which reacted strongly and exclusively with photoreceptor inner segments, but not outer segments. Immunoblot analysis of whole rat retina homogenate showed that anti-PKCα recognized an antigen of ∼ 80kD and anti-PKCξ recognized a ∼72kD protein. Immunolocalization of PKCξ to photoreceptor inner segments and possible functional significance are discussed.