HDX-MS differences upon PIKfyve ^CC binding to PI3P liposomes. (A) Peptides in the PIKfyve^CC showing significant differences in deuterium exchange (defined as >0.45 Da, >5% difference, and P < 0.01 in a two-tailed t test) upon binding to 20% PI3P/45% PC/25% PE/10% PS liposomes. Differences are mapped on the predicted structure for the PIKfyve^CC from Fig. 1 B, with an expanded view of the linker region shown below, with the linker shown as a green surface. (B) Sum of the number of deuteron differences for all peptides analyzed over the entire time course for the PIKfyve^CC upon binding PI3P liposomes. Peptides colored in red are those that had a significant change (defined as >0.45 Da, >5% difference, and P < 0.01 in a two-tailed t test). Each time point represents a single peptide, and error bars are shown as the sum of SD across all time points (n = 3 for each time point except: n = 2 for 30s membrane binding, 300s membrane 1980–2013, 300s membrane 1983–2008, 30s apo 1941–1956, 300s apo 1983–2008). The domain architecture of the PIKfyve^CC is noted above the primary sequence. The full HDX data are available in the source data. (C) Selected PIKfyve^CC peptides that showed significant increases or decreases in exchange upon binding PI3P liposomes. Mean is shown, with error bars representing SD (n = 3).