Differential expression and subcellular localization of protein kinase C isoforms in neuronal and cardiac tissues of Limulus polyphemus.

The presence and subcellular distribution of specific protein kinase C (PKC) isoforms in Limulus neuronal and cardiac tissue extracts were determined using polyclonal antibodies to individual PKC isoforms. Western blot analysis revealed that the brain, abdominal ganglia, cardiac ganglia and heart all contained PKC's alpha, beta, gamma, epsilon and zeta. PKC delta was detected in all neuronal tissues. PKC theta was found only in the cardiac ganglia and heart. PKC's gamma and delta were predominantly localized in membrane fractions while the alpha, beta, epsilon, zeta and theta isoforms were found in both fractions. Antibodies to PKC's epsilon and zeta detected relatively high molecular weight bands in membrane fractions and lower molecular weight bands in the cytosolic fractions. The results demonstrate that Limulus neuronal and cardiac tissues differentially express the conventional, novel and atypical isoforms of protein kinase C.