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Unformatted text preview: I ntercellular Communication Features of Sensing/Signaling System Specificity of Recognition o Receptor (proteins in cell membrane) and ligand (typically soluble chemicals in extracellular environment) interaction. Receptors will only bind to specific ligands. o Signal Amplification Soluble intracellular secondary messengers Secondary Messengers : usually metabolites of pre-existing cellular components Reversable protein phosphorylation o Appropriatesness or response (Acute vs. Longterm) o Graded nature of response (proportional to magnitude of stimulus) o Mechanisms of control Feed-forward and feedback (+/-) Desensitization, re-sensitization Signal transduction often involves a cascade of enzymes that attach phosphate groups to proteins Example signaling systems: Neuro/Muscular System: acetylcholine o Function: control of muscle contraction by nervous system. Chemical messenger acetylcholine is released from nerves adjacent to muscle fiber....
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- Spring '08