Structurally, the SH3 domain adopts a characteristic beta-barrel fold composed of five or six anti-parallel beta-strands. This fold creates a surface that can bind to proline-rich motifs, typically following the consensus sequence PXXP, where "P" stands for proline and "X" is any amino acid. The binding affinity and specificity are determined by the unique arrangement of residues within the SH3 domain.
