Cocrystal structure of a DENV2 sE2 with βOG. (a) Structure of a soluble prefusion dimer containing DI, DII, and DIII of DENV2 with βOG bound in the hydrophobic pocket at the interface of DI and DII (PDB:1OKE). (b) The zoomed-in view of the βOG-binding pocket (PDB:1OKE) superposed on the unliganded structure (gray; PDB:1OAN), indicating the change in the kl hairpin. (c) The zoomed-in view of the location of mutations that alter the threshold pH for fusion. Abbreviations: βOG, n-octyl-β-D-glucoside; D, domain; DENV2, dengue virus 2; sE2, soluble prefusion E dimer. Structural graphics were generated with UCSF Chimera, developed by the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco, with support from NIH P41-GM103311 (166).