Unravelling the different functions of protein kinase C isoforms in platelets.

Platelets tightly regulate haemostasis and arterial thrombosis. Protein kinase C (PKC) is involved in most platelet responses implicated in thrombus formation. Recent pharmacological and mouse gene knockout approaches show that the conventional PKC isoforms and the novel PKC isoforms contribute in distinct ways to these platelet responses. We hypothesize that, in platelets and other cells, the characteristic functions of PKC isoforms are established through unique activation mechanisms and unique interacting protein partners, which result in isoform-specific patterns of substrate phosphorylation. For identifying the substrate proteins in a living cell, new methodology is available and discussed.