Fig. 5: The N-terminal region of PRPF40A improves the selectivity of the WW domains.

A Different extended constructs of the N-terminal region of PRPF40A. B NMR titration analysis of the N-terminal extended WW12 construct with the high-affinity peptide from SF1 (SF1_WWbs): two chemical shift perturbation plots are shown for the comparison of ¹H-¹⁵N (top) and ¹H-¹³C HSQC spectra between the free and bound (1:2) states (spectra shown in Supplementary Fig. 18). The most perturbed region corresponds to the WW12 binding interface as in the WW12 titrations; but in the N-terminal extension, two regions appear also affected (due to release from WW12 intramolecular binding). Negative gray bars indicate no data. C Bar chart showing the affinities calculated by ITC for the different types of SF1 peptides with the three WW12 versions (isolated WW domains—green, N-terminal extended WW12 construct—orange, mutated version of the N-extWW12—blue). Bars indicate averaged values while individual data points are shown as black dots; all ITC titrations were done at least in duplicates for each peptide. D Plot comparing interactors of GFP-tagged PRPF40A-Nter-WT vs PRPF40A-Nter-MUT construct. In the PRPF40A-Nter-MUT construct, the proline-rich sequence was substituted by a polyalanine stretch. To remove background, only proteins that are significantly enriched for the GFP-tagged WT- or Mut-PRPF40A constructs compared to GFP alone are considered. Significantly altered protein interactions are shown in blue (log2 FC > log2(1.5), adjusted p-value < 0.05), non-significant binding differences are shown in gray. Adjusted p values (two-sided) were determined by linear modeling using the limma package. Source data are provided as a Source Data file.