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Figure 5.
Figure 5 Structure of the RGS–SAMP3 complex. (A) Final
RGS–SAMP3 2F[o] - F[c]  -calc
electron density map in the region of SAMP3 residues
Cys2043–Pro2049. The map is contoured at 1  .
(B) The SAMP3-binding site of Axin-RGS is distinct from the G[i
 ]-binding
site of RGS4. The Axin-RGS–SAMP3 complex is superimposed on
the structure of the RGS4–G[i ]complex.
Axin-RGS is red, SAMP3 is blue, RGS4 is light gray and G[i ]is
dark gray. The complex is rotated 90° perpendicular to the
page, then 180° around the vertical relative to the
orientation of Axin-RGS in Figure 4B. (C) Conservation of the
APC-binding surface of Axin-RGS. Surface representation of
Axin-RGS, colored by conservation of residues within Axin family
members. White indicates that a residue is not significantly
conserved, yellow and orange indicate residues that are
conserved or conservatively substituted, and red indicates
residues that are absolutely conserved in Axin homologs. The
SAMP3 peptide C[ ]trace
is drawn in blue. The second conserved patch referred to in the
text is visible near the top of Axin-RGS, above the
SAMP3-binding site. The complex is rotated 180° around the
horizontal relative to its orientation in (B).
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