Fig. 5: Activation of different GPCR classes.
From: Activation mechanism of the class D fungal GPCR dimer Ste2
a–c, Representative examples of GPCRs from each of the major classes are shown in the inactive state (rainbow) and active state (magenta) coupled to a G protein (grey surface; only the C-terminal α5 helix is shown). Major changes in secondary structure upon receptor activation (blue arrows) form the binding site for the α5 helix of the G protein α-subunit through either the outward movement of helices from the binding site and/or movement of helices inwards to form the binding site. a, Class A, β2-adrenoceptor37,38 (Protein Data Bank (PDB) ID 2RH1 (active) and 3SN6 (inactive)); class B, corticotropin-releasing factor receptor 139,40 (PDB ID 4K5Y (active) and 6P9X (inactive)); and class F, smoothened receptor33,41 (PDB IDs 5L7I (active) and 6OT0 (inactive)). b, Class C, type B GABA (γ-aminobutyric acid) receptor34,42 (PDB IDs 7EB2 (active) and 7C7S (inactive)). c, Class D1, Ste2 receptor1 (PDB IDs 7QA8 (active) and 7AD3 (inactive)).
