Structure of the influenza virus glycoprotein antigen neuraminidase at 2.9 Å resolution

Abstract
The influenza virus neuraminidase glycoprotein is a tetramer with a box-shaped head, 100 .times. 100 .times. 60 .ANG., attached to a slender stalk. The three-dimensional structure of neuraminidase heads shows that each monomer is composed of 6 topologically identical .beta.-sheets arranged in a propeller formation. The tetrameric enzyme has circular 4-fold symmetry stabilized in part by metal ions bound on the symmetry axis. Sugar residues are attached to 4 of the 5 potential glycosylation sequences and, in one case, contribute to the interaction between subunits in the tetramer.