Protein kinase C (PKC) isoforms in Drosophila.

Six protein kinase C (PKC) genes are present in Drosophila, comprising two classical PKCs (PKC53E and eye-PKC), two novel PKCs (PKC98E and PKCdelta), an atypical PKC (DaPKC), and a PKC-related kinase. Loss of function alleles affecting DaPKC and eye-PKC are available and their mutant phenotypes have been characterized. DaPKC is essential for early embryonic development because it regulates cell polarity and asymmetric cell division. Eye-PKC plays a role in the regulation of visual signaling, a G-protein coupled phospholipase Cbeta-mediated cascade. Both eye-PKC and DaPKC are differentially localized through tethering to multimolecular complexes. DaPKC interacts with partitioning-defective 3 (Par-3) and Par-6 proteins, which contain PDZ (PSD95, DLG, ZO-1) domains. Similarly, eye-PKC is anchored to a PDZ domain containing scaffolding protein INAD. Characterization of these two PKCs in Drosophila revealed a universal mechanism by which PKC is tethered to specific protein complexes for participation in distinct signal transduction processes.