|
Figure 2.
(a) Cartoon representation of the complex of HHIP[  12]
(green) and SHH (pink). The three loops from HHIP[ 12]
contacting SHH are labeled L1–L3. Zn^2+ and Ca^2+ cations are
shown as gray and cyan spheres, respectively. The N and C
termini of SHH, and the C terminus of HHIP, are all on the same
side of the complex, suggesting that both components could be
anchored to the same cell membrane. See Supplementary Figure 3a
for a 90°-rotated version. (b) Alanine mutants in HHIP loops
that contact SHH. Residues that were mutated to alanine are
shown as spheres, with those that abolished SHH binding shown in
red, those that had a notable impact shown in orange and those
with minimal consequence shown in yellow. (c) Coordination of
the Zn^2+ cation by residues from SHH and HHIP[ 12].
Key residues are shown as sticks, with nitrogen atoms colored
blue and oxygen atoms colored red. Zn^2+ (gray sphere) is
coordinated by residues His140, Asp147 and His182 from SHH
(pink) and Asp383 from HHIP[ 12]
(green). (d) The SHH Zn^2+-containing groove and the Ca^2+
binding site are distinct. SHH and HHIP are colored pink and
green, respectively, with a transparent surface shown for the
HHIP L2 loop. Zn^2+ and Ca^2+ cations are shown as gray and cyan
spheres, respectively. SHH residues, which in IHH are
genetically associated with brachydactyly type A1, are shown as
sticks, and carbon atoms are colored either yellow
(Zn^2+-containing groove) or orange (Ca^2+-coordinating) and are
numbered according to human SHH. (e) Inhibition of SHH signaling
in Gli-luciferase co-culture assays by HHIP[ 12]
mutants. Assays were carried out as in Figure 1b. Results are
plotted as the average of three independent triplicates
normalized to 100% for the 'no inhibitor' data point,  s.d.
|
