| Docking of the proline rich peptide , 3BP1 on Grb 2 N SH 3 , shows that the polyproline type 2 helix can bind the SH 3 domain forming conserved hydrogen bonds between the main chain carbonyl oxygens of Met 4 and Pro 7 of the proline rich peptide and the reoriented side chains of Trp 36 and Asn 51 , respectively , and a hydrogen bond between the main chain carbonyl of Leu 8 of the proline rich peptide with the side chain OH of Tyr 52 of the Grb 2 N SH 3 . ^^^ |