One of the stretches of prolines in B4-2 closely resembles the ligand for proteins with SH3 domains .
one of the stretches of prolines in b4-2 closely resembles the ligand for proteins with sh3 domains .
O O O O O B-amino_acid_monomer O B-DNA_molecule O O O O O O O B-protein_domain_or_region I-protein_domain_or_region O