Biology of heterotrimeric G-protein signaling

The G proteins are components of a complex membrane signaling system designed to modulate extracellular signals as they are transmitted into the cell. The principal components are the receptor, the G proteins including the alpha, beta, gamma subunits and the effector. Associated with these molecules are several molecular processes by which the signal is transmitted, and regulated including desensitization. Molecules such as arrestin, the RGS (regulators of the G-protein signaling) as well as downstream kinases associated with cyclic AMP are key to regulating the G protein signal. Membrane lipids are key for both anchoring this signal system to the plasma membrane but also in defining the signaling process. Through understanding the biology of the signal system, a number of diseases have been linked to dysfunction of the G protein system. It is clear that this important membrane signal system will become the target for more intense investigation and pharmacologic manipulation to treat critical illness.