ABSTRACT
The discovery of AGS proteins indicates that G-protein-dependent signaling is considerably more complex and connected with other signaling pathways to a much higher degree than hitherto assumed. Membrane targeting plays an essential role for the recruitment of signal-processing protein complexes to transmembrane receptors as well as for protein sorting within the different membrane compartments of the cell. The ceramide effector proteins include both protein phosphatases and protein kinases. Trimeric G-proteins couple a large number of membrane receptors to the data-processing protein network of the cell. They do this mainly by controlling the activities of enzymes that catalyze the generation of second messengers. Three types of intracellular cyclic guanosine 3',5'-monophosphate (cGMP) receptors have been identified: cGMP-activated protein kinases, cGMP-controlled phosphodiesterases, and cGMP-controlled ion channels. In bacteria, one major task of cellular data processing is to cope with environmental stress to discriminate between good and bad influences.
