The carboxyl-terminal sequence of the heavy chain of a Hong Kong influenza haemagglutinin.

The reduced carboxymethylated heavy chain (HA1) of a Hong Kong influenza haemagglutinin (H3) was digested with cyanogen bromide to give five peptides. The sequences of three of these peptides, together with the sequences of two methionine overlap peptides were combined to give the C-terminal 68-residue sequence of the heavy chain. Threonine is the C-terminal residue of the heavy chain, an unexpected result in view of the generation of the heavy and light chains by the proteolytic cleavage of a pro-haemagglutinin during virus assembly. Three half-cystine residues occur close together at positions 24, 48 and 52 residues in from the C-terminus. A carbohydrate group is attached to an asparagine residue 44 residues from the C-terminus; it contains 5 residues mannose and 2 residues glucosamine.