title: Three-dimensional structure of neuraminidase of subtype N9 from an avian influenza virus.
abstract: Neuraminidases from different subtypes of influenza virus are characterized by the absence of serological cross-reactivity and an amino acid sequence homology of approximately 50%. The three-dimensional structure of the neuraminidase antigen of subtype N9 from an avian influenza virus (A/tern/Australia/G70c/75) has been determined by X-ray crystallography and shown to be folded similarly to neuraminidase of subtype N2 isolated from a human influenza virus. This result demonstrates that absence of immunological cross-reactivity is no measure of dissimilarity of polypeptide chain folding. Small differences in the way in which the subunits are organized around the molecular fourfold axis are observed. Insertions and deletions with respect to subtype N2 neuraminidase occur in four regions, only one of which is located within the major antigenic determinants around the enzyme active site.
authors.affiliation: CSIRO Division of Protein Chemistry, Parkville, Victoria, Australia.
authors.forename: A T
authors.initials: AT
authors.lastname: Baker
authors.forename: J N
authors.initials: JN
authors.lastname: Varghese
authors.forename: W G
authors.initials: WG
authors.lastname: Laver
authors.forename: G M
authors.initials: GM
authors.lastname: Air
authors.forename: P M
authors.initials: PM
authors.lastname: Colman
mesh_terms: D000595:Amino Acid Sequence; D000956:Antigens, Viral; D001665:Binding Sites; D009980:Influenza A virus / Q000145:classification / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid; D009439:Neuraminidase / Q000276:immunology / Q000378:metabolism; D011487:Protein Conformation; D012794:Sialic Acids / Q000378:metabolism
chemical_list: D000956:Antigens, Viral; D012794:Sialic Acids; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid