Transport and inhibition mechanism for VMAT2-mediated synaptic vesicle loading of monoamines

Structural determination assisted by ALFA-tag/nanobody

Human VMAT2 (55 kDa) contains a membrane domain with 12 transmembrane helices (TMs) and lacks discernable extramembrane domains (Supplementary information, Fig. S1a), posing a significant challenge for structural characterization by cryo-EM. For similarly small and featureless proteins, various approaches have been employed to increase the effective size, including specific nanobodies or antibody fragments (Fabs),^24,25,26 fusion with a large rigid domain like BRIL or GFP,^26,27 and/or extending the N-terminal TM of target proteins…