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Figure 1.
Fig. 1. Comparison of the inactive G  ß  heterotrimer and
the G [i/q]-GRK2-Gß
complex. (A) Side
view of G [q]ß .
G [q]ß was homology
modeled by using the structure of G [i]ß[1]
[2] (5). The
expected membrane surface is modeled as a gray rectangle that
extends out from the plane of the figure (31), and the
heterotrimer is oriented as proposed in (6). G [q] is cyan with
orange ß-strands, Gß is blue, and G is
green. The three switch regions (labeled I, II, and III) and the
N-terminal helix of G [q] are red and
yellow, respectively. GDP and G [q]-Cys9 and
Cys10, which can be palmitoylated, are shown as ball-and-stick
models. (B) Top view of G [q]ß from the
perspective of the modeled membrane surface. (C) Side view of
the G [i/q]-GRK2-Gß
complex. For
purposes of comparison, GRK2-bound Gß was centered in
the same position as Gß in panel (A). The
chimeric N-terminal helix of GRK2-bound G [i/q] is
disordered in the crystal structure. The kinase domain of GRK2
is yellow with olive ß strands, the RH domain is purple,
and the PH domain is tan. Mg2+ (black sphere) and AIF[4]^-
(green and magenta) are bound in the active site of G [i/q]. (D) Top
view of the G [i/q]-GRK2-Gß
complex from the
same orientation as (B). Residues 114 to 121 in 5
of GRK2 (shaded pink) alter their conformation upon docking with
the effector-binding pocket of G [i/q] (see SOM
text).
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