1H-15N HSQC spectrum of Itk SH3 at pH 7.4, 298K. Backbone and side chain NH assignments are indicated using the one letter amino acid code and full length Itk numbering. Side chain residues are labeled with Hε1 for tryptophans (W208 and W209), Hδ2 for asparagines (N232, N185, and N215) and Hε2 for glutamines (Q212, Q183, and Q188)