Peptide Hormone Receptors
Many hormones are composed of polypeptides, e.g. thyroid-stimulating hormone, follicle-stimulating hormone, leutinizing hormone and insulin. These molecules are not lipid-soluble and therefore cannot diffuse through cell membranes. Consequently, receptors for peptide hormones are located on the plasma membrane.
Peptide hormone receptors are often transmembrane proteins. They are also called G-protein-coupled receptors, sensory receptors or ionotropic receptors. These receptors generally function via intracellular second messengers, including cyclic AMP (cAMP), inositol 1,4,5-trisphosphate (IP3) and the calcium (Ca2+)-calmodulin system.
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Famous quotes containing the word receptors:
“Our talk of external things, our very notion of things, is just a conceptual apparatus that helps us to foresee and control the triggerings of our sensory receptors in the light of previous triggering of our sensory receptors.”
—Willard Van Orman Quine (b. 1908)