Structure and orientation of expressed bovine coronavirus hemagglutinin-esterase protein

The sequence of the hemagglutinin-esterase (HE) gene for the Mebus strain of bovine coronavirus was obtained from cDNA clones, and its deduced product is a 47,700-kilodalton apoprotein of 424 amino acids. Expression of the HE protein in vitro in the presence of microsomes revealed N-terminal signal peptide cleavage and C-terminal anchorage but not disulfide-linked dimerization. Dimerization was observed only after expression in vivo, during which HE was also transported to the cell surface.