STRUCTURE AND EXPRESSION OF A NOVEL, NEURONAL PROTEIN-KINASE-C (PKC1B) FROM CAENORHABDITIS-ELEGANS - PKC1B IS EXPRESSED SELECTIVELY IN NEURONS THAT RECEIVE, TRANSMIT, AND PROCESS ENVIRONMENTAL SIGNALS

The nematode Caenorhabditis elegans provides an advantageous system fo r investigating the regulation, expression, and functions of protein k inase C (PKC) isoforms. We cloned and characterized cDNAs encoding a n ovel C. elegans PKC designated PKC1B. The predicted PKC1B polypeptide contains features characteristic of the nPKC subfamily of PKC isoforms . The levels of PKC1B and its cognate mRNA vary over a 7-fold range du ring C. elegans postembryonic development. PKC1B protein and mRNA are abundant at the earliest larval stage, but their relative concentratio ns decrease coordinately in late larvae. Embryos, which are enriched i n PKC1B mRNA, contain little PKC1B protein. Thus, PKC1B expression is regulated at a translational or post-translational level during early development. Cells engaged in PKC1B gene transcription were identified in transgenic C. elegans that carry the lacZ gene under the regulatio n of the PKC1B promoter. Staining for beta galactosidase revealed PKC1 B promoter activity exclusively in sensory neurons and interneurons. I mmunofluorescence microscopy disclosed that the PKC1B polypeptide is l ocated in the processes (axons and dendrites) and perinuclear regions of similar to 75 neurons that constitute the sensory circuitry of the nematode. The intracellular lo calization of PKC1B and the enzyme's di fferential solubility in ionic and nonionic detergents suggest that th e kinase is associated with membranes and the cytoskeleton.