THE ENVELOPE GLYCOPROTEIN FROM TICK-BORNE ENCEPHALITIS-VIRUS AT 2 ANGSTROM RESOLUTION

The crystallographically determined structure of a soluble fragment fr om the major envelope protein of a flavivirus reveals an unusual archi tecture. The flat, elongated dimer extends in a direction that would b e parallel to the viral membrane. Residues that influence binding of m onoclonal antibodies lie on the outward-facing surface of the protein. The clustering of mutations that affect virulence in various flavivir uses indicates a possible receptor binding site and, together with oth er mutational and biochemical data, suggests a picture for the fusion- activating, conformational change triggered by low pH.