Fig. 5: High resolution SNR data analysis using rigid-body modeling with AP2 crystal structures identifies open conformation as the preferred orientation and conformation of AP2 bound to cargo and PtdIns(4,5)P₂ enriched monolayers.

A Volume fraction profiles for open (PDB 2ax7) and close (PDB 2vgl) conformation of AP2. B Experimental SNR profile in NRM compared to a theoretical profile calculated for open (red, (C) conformation, based on the best possible orientation of the protein bound to the lipid monolayer. Heat map evaluating the different protein orientations for open, open+ and close conformations as a function of the α and β Euler angles for intrinsic rigid body rotations of AP2 are shown in Figures S15–S17, respectively. D Calculated volume fraction profiles corresponding to the preferred orientation of open conformation AP2 bound to PtdIns(4,5)P₂-enriched monolayers in absence and presence of TGN38 or CD4 peptides. E Fractional surface coverage of AP₂ for each orientation, derived from the analysis in (D) for CD4, TGN, and PtdIns(4,5)P₂-enriched monolayers (presented as mean ± standard deviation (SD), n = 256). Individual data points can be found in the source data. F Violin plots show the distance to the interface, calculated by fitting the theoretical and experimental SLD values for each orientation of the protein in open conformation (PDB: 2xa7). The width of each violin represents the probability density of the data at different values. Embedded within each violin, a miniature box plot displays the median (central dot), with the box spanning the interquartile range (IQR, from the 25th to the 75th percentile), and whiskers extending to the most extreme data points within 1.5 times the IQR. (n = 256).