Homodimer. In infected cells becomes incorporated into the envelope of virions during virus assembly at the endoplasmic reticulum and cis Golgi. However, some may escape incorporation into virions and subsequently migrate to the cell surface (By similarity). N-glycosylated. The truncated hemagglutinin-esterase of Berne virus is probably non-functional, since part of its active site is missing. Belongs to the influenza type C/coronaviruses hemagglutinin-esterase family.