title: The Ras binary switch: an ideal processor for decoding complex Ca2+ signals?
abstract: Activation of cell-surface receptors often leads to changes in intracellular calcium concentration ([Ca(2+)](i)). Receptor-generated calcium transients are often seen as repetitive spikes of elevated intracellular calcium concentration ([Ca(2+)](i)), whose frequency varies according to the amplitude of the receptor stimuli. This suggests a requirement for molecular decoders, capable of interpreting such complex calcium signals into the correct physiological response. Ras proteins are binary molecular switches controlling a plethora of cellular responses. Whether Ras is in its active GTP-bound, or inactive GDP-bound, form is determined by the activity of guanine nucleotide exchange factors (GEFs) and GTPase-activating protein (GAPs). Calcium-regulated GEFs and GAPs have been identified, some with an exquisite sensitivity to [Ca(2+)](i), implicating a potential role of complex calcium signals in regulating Ras.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division; D002462:Cell Membrane / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D015398:Signal Transduction; D020703:ras GTPase-Activating Proteins / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D020703:ras GTPase-Activating Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D018631:ras Proteins; D002118:Calcium