Cell-surface receptors can bind hormones and affect GTP-binding proteins {G protein} inside cell membranes. Activated G protein catalyzes its return to unactivated state, thus timing rate of G-protein processes. Immediate-early genes activated in learning use cAMP signal paths.
cyclic AMP
G protein uses GTP to activate adenylate cyclase and make cAMP. cAMP affects protein kinase A, which then phosphorylates CRE-binding protein, which binds to cAMP response elements (CRE).
senses
Olfactory sensors use G-protein transduction.
structure
G protein is similar to proteins for cross-membrane signaling, protein synthesis, cell molecule transport, and cross-membrane transport.
Steroid-receptor proteins bind to regulatory-region 15-base sequences {hormone-response element}, for activation or repression.
Chemicals {ionophore} can artificially raise cell calcium concentration.
Serine proteinases {plasminogen activator} can have cell-surface receptors. Urokinase plasminogen activator (uPA) can activate matrix metalloproteinases. Plasminogen-activator inhibitors counteract tissue plasminogen activator (tPA).
Retina rod-cell proteins {rhodopsin}| can absorb light and bind GTP to transducin, which activates phosphodiesterase, which breaks down cGMP, which closes cGMP-dependent ion channels and so causes hyperpolarization. Rhodopsin is similar to adrenergic receptor. Opsin proteins are similar to rhodopsin, because both use 11-cis-retinal as chromophore. Absorption maximum differs for opsins and rhodopsin.
GTP-binding proteins {transducin} can transduce signals in eye.
ATR protein, matrilins, integrins, and other cell-surface protein-interaction proteins have extra-cellular domains {von Willebrand factor type A}.
4-Genetics-Gene-Cell Surface Receptor
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Date Modified: 2022.0225