PMID: 9851931 , Related PDB ids: 1B07, 2SEM, 3SEM
Nguyen JT, Turck CW, Cohen FE, Zuckermann RN, Lim WA
Exploiting the basis of proline recognition by SH3 and WW domains: design of N-substituted inhibitors.
Science. 1998 Dec 11;282(5396):2088-92.
Src homology 3 (SH3) and WW protein interaction domains bind specific proline-rich sequences. However, instead of recognizing critical prolines on the basis of side chain shape or rigidity, these domains broadly accepted amide N-substituted residues. Proline is apparently specifically selected in vivo, despite low complementarity, because it is the only endogenous N-substituted amino acid. This discriminatory mechanism explains how these domains achieve specific but low-affinity recognition, a property that is necessary for transient signaling interactions. The mechanism can be exploited: screening a series of ligands in which key prolines were replaced by nonnatural N-substituted residues yielded a ligand that selectively bound the Grb2 SH3 domain with 100 times greater affinity.