(A–B) Ribbon models of a Snf7 protofilament. The hydrophobic protein interface is shown in black dash-line and the electrostatic interface in grey dash-dot line. (C–D) Close-up views of the hydrophobic interface between α2/3i and α3i+1 and the electrostatic interface between α1i and α2/3i+1. Protomer (i) shown in yellow and protomer (i+1) in red. (E) Conceptual model for the Mup1-pHluorin MVB sorting assay. Vacuole (v). (F) Quantitative MVB sorting data for snf7Δ yeast exogenously expressing empty vector, SNF7, snf7L121D, snf7I117E, snf7M114E, snf7M107E, snf7T103E, snf7L99K, snf7M104E, snf7L101E, snf7A97K, snf7I94E, snf7Q90K, snf7M87E, and snf7T83E. Error bars represent standard deviations. (G) Quantitative MVB sorting data for snf7Δ yeast exogenously expressing empty vectors, SNF7, snf7R25E H29E K36Eand empty vector, empty vector and snf7E95K E102K E109K, and snf7R25E H29E K36E and snf7E95K E102K E109K. Error bars represent standard deviations. (H) Representative TEM images of recombinant full-length Snf7R52E, Snf7R52E Q90K, Snf7R52E M107E, Snf7R52E R25E H29E K36E, Snf7R52E E95K E102K E109K, and Snf7R52E R25E H29E K36E and Snf7R52E E95K E102K E109K (1:1). Scale bars, 200 nm.