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Figure 4.
Figure 4. Hydrogen Bonds Surrounding cAMPThe network of
conserved and nonconserved hydrogen bonds surrounding the two
cAMP binding sites of RIIb.(a) Binding site A.(b) Binding site
B. Cyclic AMP molecules are rendered as balls and sticks with
gray for carbon, blue for nitrogen, red for oxygen, and purple
for the phosphorous atom. Hydrogen bonding is represented by
dashed lines. Water oxygen atoms are illustrated as ovals with
gradient shading and the uniquely identifying three-digit
numeral assigned by the PDB file 1cx4. Tan-shaded boxes signify
secondary structural elements identified in Figure 3; the labels
for these boxes are either red for b strands or green for a
helices. The regions encompassed by yellow lie within the
conserved phosphate binding cassette. Amino acid residues with
more than one hydrogen-bonding atom are boxed and labeled in
either blue for invariant residues or black for nonconserved
residues
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