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Figure 5.
Figure 5. (a) The 3D structures of the N-SH3 domains of Grb2 complexed with the proline-rich peptide
VPPPVPPRRR. Left, C32S-Y7V Grb2 N-SH3 mutant; right, reference domain. The interacting side-chains from the
proline-rich peptide are in red, the peptide backbone is in yellow, the interacting side-chains from the SH3 domain
are in orange, and the backbone of the SH3 is in blue. The essential differences appear at the level of subsite S1,
which comprises amino acid residues Y7 and Y52 in the reference domain and interacts with Pro2 of the peptide.
When Y7 is mutated as V7, the proline-rich peptide interacts with V7 and Y52 side-chains by means of Pro3 ring
instead of Pro2. (b) Superposition of the 3D structures of the N-SH3 domains of Grb2 complexed with the proline-
rich peptide: in yellow, the reference domain and in red, the mutant domain. Only tyrosine 7 or valine 7 are shown.
It appears that the difference is mainly in the way the peptide binds the protein.
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