Signalling to the nucleus via A-kinase anchoring proteins.

The cell nucleus is a highly dynamic organelle whose function and structure during the cell cycle is tightly controlled. A number of signals triggered by external stimuli or intracellular clocks are relayed to the nucleus by protein kinases and phosphatases. Specificity of action of kinases and phosphatases can be achieved by their recruitment into multiprotein complexes targeted to discrete subcellular or subnuclear loci. One class of molecules targeting signalling units within single complexes are A-kinase anchoring proteins or AKAPs. AKAPs not only target enzymes to their substrate but may also regulate enzyme activity. This chapter highlights the role of nuclear AKAPs in relaying and modulating protein kinase and phosphatase signals to the nucleus or chromosomes.