Protein kinase C localization in the synaptic terminal of rod bipolar cells.

The purpose of the present study was to elucidate the physiological mechanisms that determine the activation of protein kinase C (PKC) in rod bipolar cells (RBC) of mouse and goldfish. The localization of PKC in RBC was examined using immunoreactivity (IR) against the alpha species of the enzyme. After incubating the whole retina or dissociated cells in control or test solutions, PKC-IR was performed on retinal transverse sections or on isolated cells. Cell depolarization induced the transport of the PKC to the synaptic terminal of RBC. The transport of the enzyme was also induced upon incubating dissociated cells in a solution containing phorbol esters. Enzyme transport was inhibited when the isolated retina was incubated in solutions containing GABA or nifedipine. We conclude that calcium and diacylglycerol, which contribute to the activation of PKC in RBC, induce transport of the enzyme to the synaptic terminal where it is presumed to play its functional role.