Cartoon representation of the binding pocket of JAK3 with inhibitor 52 (a) and 57(b). In inhibitor 52, dipyrrolopyridine moiety develops hydrogen bond to the GLU 903 while its furanamide moiety interacts with ARG 953 and ASN 954 from the lower lobe as well as LYS 830 from the upper lobe. The inhibitor also makes a hydrogen bond to CYS 909. b): Dipyrrolopyridine moiety develops three hydrogen bonds to the GLU 903 and LEU 905 of the hinge residues. Hydrogen bonding is also seen with ASN 832 from the upper lobe and ARG 953 and CYS 909 from the lower lobe. Hydrogen bonding is represented by dotted lines.