Fig. 4.

Allosteric mutants alter acid loop conformation. BB3 titration and distal mutants of PTP1b both shift the acid loop into an inactive state. Cartoon rendering of PTP1B (PDB ID: 1PTT, 2HNP) is shown where the acid loop is affected by (a) BB3 ligand shown in stick and (b) distal mutations shown in cyan spheres. Gray spheres represent the network detected through alanine loop mutant analysis. (c–e) Acid loop resonances of distal mutations overlaid with WT apo (open) and closed conformations. (f–h) Acid loop resonances of a BB3 titration overlaid with resonances in the closed conformation from a tungstate titration. The protein backbone was rendered in Pymol [52].