Colour-coded backbone hydrogen and nitrogen chemical shift differences between the single PDZ2-APC complex and PDZ2-APC when being part of the PDZ2/3-APC complex. The analysis is based on the structure of the single PDZ2 domain . The α-helices DA and DB correspond to α1 and α2, and the β-strands EA, EB, EC, ED, EE, and EF correspond to β1 to β6, respectively. According to the given scale, the yellow to red colour gradient of the ribbon structure represents smaller to larger NMR chemical shift differences. Gray colouring indicates that either no chemical shift differences were observed or no data were available.