Fig. 8. Hypothetical model of the subcellular targeting of PKC. PKC translocation to the plasma membrane is regulated through at least two distinct mechanisms: a selective targeting to cell-cell contacts mediated through the C2-V3 region (and at least the V3 domain of ) and a non-selective targeting to the entire plasma membrane involving the V1 and the pseudosubstrate domains. In both cases the translocation to the plasma membrane may require the release of PKC from a cytoplasmic anchoring protein, which should be a RICK. This protein, involved in the cytoplasmic sequestration of PKC, would interact with the C2-V3 region and possibly also with the pseudosubstrate region. Once released from binding to the cytoplasmic anchoring protein, C2-V3 would bind another protein, a RACK, whose expression or ability to bind to PKC is induced by cell-cell contacts. This protein may be either a shuttle or a cargo/anchoring protein that selectively targets PKC to cell-cell contacts upon stimulation. RICK, receptor for inactive c-kinase; RACK, receptor for active c-kinase; Ad J, adherens junctions; ECM, extracellular matrix; DAG, diacylglycerol.