Mutation of a raft-targeting signal in the transmembrane region retards transport of influenza virus hemagglutinin through the Golgi

Inclusion of proteins into membrane-rafts favours interactions required for virus assembly but has also been proposed to facilitate vesicular transport of proteins. The hemagglutinin (HA) of influenza virus contains a raft-targeting sequence in the outer leaflet of its transmembrane region. We report that its mutation enhances co-localization of HA with a cis-Golgi marker and retards Golgi-localized processing, such as acquisition of Endo-H resistant carbohydrates and proteolytic cleavage. In contrast, trimerization of the molecule in the ER and transport to the apical membrane were not affected. The second signal for raft-targeting, S-acylation at cytoplasmic cysteines, did not retard HA transport.

► Hemagglutinin of influenza virus associates with rafts of the plasma membrane. ► A raft-targeting signal in the outer part of the transmembrane region was mutated. ► Processing of HA and co-localization with a Golgi-marker was analyzed. ► Transport through the Golgi, but not trimerization in the ER, was retarded. ► The second signal for raft-targeting, S-acylation, had no effect on transport.