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Unformatted text preview: • Ligand binds to inactivate receptor • Active GPCR has conformational change. • GPCR interacts with the alpha subunit of an inactive GDP-bound G protein • Alpha subunit has a conformational change which causes a high affinity for GTP • Conformational change causes GTP-bound active G protein. GTP addition mediates dissociation of alpha subunit form beta and gamma subunits • GTP-bound Alpha subunit regulates target proteins • GTP is hydrolyzed • G-alpha subunit reassembles to make inactive G protein 3. When a cell releases a signal molecule into the environment and a number of cells in the close vicinity respond, this type of signaling is A) typical of hormones. B) autocrine signaling. C) synaptic signaling. D) paracrine signaling. E) endocrine signaling. Autocrine signaling—when a cell releases a signal that acts upon itself Paracrine—acts LOCALLY only. Released in contained manner...
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- Winter '08
- cell biology, GTP, alpha subunit, Autocrine Signaling