Potential roles of heterotrimeric G proteins of the endomembrane system.

Heterotrimeric G proteins are recognized as versatile switches linking cell surface receptors to cellular effectors. Beside their location at the plasma membrane G proteins are found on intracellular membranes. Studies with modulators of G protein activity suggest that G proteins associated with organelle membranes are involved in various steps of secretion and vesicular function. In contrast to hormonal responses involving G proteins little is currently known about possible receptors or activators and effectors interacting with intracellular G proteins. This short review focuses on recent developments elucidating the role of organelle-associated G proteins.