Fig. 4.

The acidic head of CC mediates interaction with ZO-1. (A) Close-up of TROSY spectrum of perdeuterated [¹⁵N]-apo (red) CC overlaid with PSG-bound perdeuterated [¹⁵N]-CC (black) showing the shifts for residues affected by the addition of CC (Y467, A478) and those unaffected (K433). (B) 1D traces of the residues in A from cross-saturation relaxation experiments for saturation at 15 ppm (red) and 1 ppm (black). (C) The in vitro capture efficiency of PSG by GST-CC is reduced by charge reversals at residues 465/469, 470, 472, and 473 in the acidic head of CC. (D) The variant GST-CC, except K433D, had a similar effect upon the capture of full-length ZO-1 from MDCK lysates. Relative binding (below the gel) was the intensity ratio of the ZO-1 band in each lane and the wt condition.