Characterization of severe acute respiratory syndrome coronavirus membrane protein

The coronavirus membrane protein (M) is the key player in the assembly of virions at intracellular membranes between endoplasmic‐reticulum and Golgi‐complex. Using a newly established human monoclonal anti‐M antibody we detected glycosylated and nonglycosylated membrane‐associated M in severe acute respiratory syndrome‐associated coronavirus (SARS‐CoV) infected cells and in purified virions. Further analyses revealed that M contained a single N‐glycosylation site at asparagine 4. Recombinant M was transported to the plasma membrane and gained complex‐type N‐glycosylation. In SARS‐CoV infected cells and in purified virions, however, N‐glycosylation of M remained endoglycosidase H‐sensitive suggesting that trimming of the N‐linked sugar side chain is inhibited.