[Membrane receptors and G regulatory proteins].
The article summarizes new findings concerning membranous receptor-effector complexes that are stimulated by various extracellular signals like hormones, neurotransmitters, growth factors, etc. Central role in this transmembranous signalling process play so-called G regulatory proteins (they bind GTP), that ensure the activation-deactivation processes between receptor and effector (enzymes or ion channels). The examples of intracellular signals ("second messengers") are cyclic AMP, inositol-trisphosphate, diacylglycerol or the accumulated ions (e. g. Ca2+). G regulatory proteins are composed of three subunits: receptor activation leads to their dissociation and the released alpha subunit with bound GTP activates the appropriate effector. Its inactivation occurs after GTP degradation by the intrinsic GTPase activity of alpha subunit which then associates with beta gamma subunits. New findings concerning the regulatory role of G proteins enable the explanation of mutual relations between various membranous receptor-effector complexes and further they also serve as basis for the explanation of some clinical disorders that are called "receptor diseases".
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D000818:Animals; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015290:Second Messenger Systems; D015398:Signal Transduction
D011956:Receptors, Cell Surface; D019204:GTP-Binding Proteins
Membránové receptory a G regulacní proteiny.