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Figure 3.
Figure 3 Comparison of the Cdc42Hs  GMPPNP/p50rhoGAP
complex with the structure of transducin-  GTP
 S.
Here, Cdc42Hs is shown in blue, with rhoGAP in red and
transducin- in
white. Transducin- consists
of two domains: one is structurally homologous to the small
GTPase family and the other is a smaller -helical
domain unique to the heterotrimeric G-protein family.
Least-squares overlap28 of Cdc42Hs with the GTPase domain of
transducin gives an r.m.s. fit of 1.7  ring
for 122 structurally equivalent C atoms.
Arg 174 has been proposed to be involved in transition-state
stabilization during GTP hydrolysis in transducin. Its C position
is shown in yellow and is positioned within a piece of extended
structure corresponding to the effector or switch I region of
Cdc42Hs (magenta). In contrast, Arg 85[r], which appears to
fulfil a similar role in GTPase activation by p50rhoGAP, is
situated on the A-Al loop on the opposing face of the
triphosphate moiety of the nucleotide analogue.
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