Biology of heterotrimeric G-protein signaling

The G proteins are components of a complex membrane signaling system design ed to modulate extracellular signals as they are transmitted into the cell. The principal components are the receptor, the G proteins including the al pha, beta, gamma subunits and the effector. Associated with these molecules are several molecular processes by which the signal is transmitted, and re gulated including desensitization. Molecules such as arrestin, the RGS (reg ulators of the G-protein signaling) as well as downstream kinases associate d with cyclic AMP are key to regulating the G protein signal. Membrane lipi ds 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 sy stem will become the target for more intense investigation and pharmacologi c manipulation to treat critical illness.