Mechanisms of multifunctional signalling by G protein-linked receptors.

A number of G protein-linked receptors have recently been shown to regulate multiple effector pathways both when expressed endogenously and, more frequently, following transfection into heterologous systems. The mechanisms responsible for such signal bifurcation are beginning to be unravelled. In this Viewpoint article, Graeme Milligan analyses the information on these mechanisms and considers whether they are dependent upon either levels of expression of the receptor or the cell type.