MODES OF INTERACTIONS BETWEEN SIGNALING PATHWAYS

The study of signaling pathways has begun to uncover the mechanism by which cells respond and adapt to extracellular stimuli. It has become increasingly clear that the signaling pathways interact with one anoth er to form a complex network through which regulation occurs. Here, we focus on three mechanisms by which signaling pathways interact and th e physiological consequences of these interactions. Coincident signali ng in long-term depression of synaptic responses in the cerebellum, pr otein kinase A gating of Ras to mitogen activated protein kinase signa l flow in proliferative responses, and a modified gating mechanism by phosducin resulting in feedback regulation of signal flow from rhodops in to the cGMP phosphodiesterase in retinal light adaptation are analy zed as examples of different types of interactions between signaling p athways. These interactions allow the cell to spatially and temporally integrate complex information and respond in an appropriate and defin ed manner. (C) 1998 Elsevier Science Inc.