MoBio G-protein-Coupled Receptors Chapter 2

The major role of G-protein-coupled receptors is to transmit signals into the cell (Chapter 6 Section D). They are characterized by seven transmembrane segments. This class of membrane proteins can respond to a wide range of agonists, including photon, amines, hormones, neurotransmitters and proteins. Some agonists bind to the extracellular loops of the receptor, others may penetrate into the transmembrane region.

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Figure 2-F-1. (a) Schematic drawing of the transmembrane topology of the G-protein-coupled receptor, which is characterized by seven transmembrane segments. (b) The structure of the beta-2 adrenergic receptor. [Source: Wikipedia]