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Figure 2.
Figure 2: Nucleic-acid-binding surface of the Ago2 PAZ domain.
a, Surface representation of the PAZ domain coloured by
sequence conservation (compare with Supplementary Fig. S1). High
to low sequence conservation is coloured from magenta to white,
respectively. b, Surface representation of the PAZ domain
coloured by electrostatic charge. White, blue and red
corresponds to neutral, positive and negative electrostatic
potential, respectively. c, NMR titration of the PAZ domain with
a single-stranded siRNA (siRNA-1as). The 1H-15N correlation
spectrum of the free protein and at sixfold molar excess of
siRNA is shown in blue and red, respectively. Green arrows
indicate the direction of peak movements. The insert shows
additional spectra at 0.5-, 1-, 1.5- and 3-fold molar excess of
RNA. p.p.m., parts per million. d, RNA-binding site on the PAZ
domain based on the NMR titration in c. Prolines or residues
that could not be analysed owing to signal overlap are shown in
yellow; residues where signals disappear at 1:0.5 molar
protein:RNA ratio are coloured green. Other residues are
coloured with a gradient from green to white according to the
degree of chemical shift changes. In all panels the same
orientation as in Fig. 1b is shown.
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