The hemagglutinin HA1 protein is essential for attachment of virions to host cells by binding to sialic acid-containing receptors, inducing virion internalization via clathrin-dependent or clathrin- and caveolin-independent pathways.As a class I viral fusion protein, HA1 determines host range restriction and virulence, mediating fusion between the virion membrane and the endosomal membrane.HA1/Hemagglutinin Protein, H5N1 (AEO89181, HEK293, His) is the recombinant Virus-derived HA1/Hemagglutinin protein, expressed by HEK293 , with C-His labeled tag.
