Ligand affinity agonist-receptor binding, dissociation

Fig. 1. Classical AR signaling. (A) In the absence of agonist, ARs are in the low-affinity state, and G proteins form a heterotrimeric complex bound to guanosine 5 -diphosphate (GDP). Ligand binding allows the formation of a transient complex of activated receptor and G protein. GDP is released from G proteins and is replaced by guanosine 5 -triphosphate (GTP). (B) This leads to dissociation of G proteins into Ga-and G -subunits and activation. Both subunits are able to activate different effectors. (See Color Plate 2 following p. 148.)...

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