Viral structural proteins

thumb|300px|Illustration showing influenza virus attaching to [[cell membrane via the surface protein hemagglutinin]] The term hemagglutinin (alternatively spelt haemagglutinin, from the Greek , 'blood' + Latin , 'glue') refers to any protein that can cause red blood cells (erythrocytes) to clump together ("agglutinate") in vitro. They do this by binding to the sugar residues on a red blood cell; when a single hemagglutinin molecule binds sugars from multiple red blood cells, it "glues" these cells together. As a result, they are carbohydrate-binding proteins (lectins). The ability to bind red

thumb|The genome organisation of HBV; the genes overlap. ORF S, in green, encodes HBsAg. thumb|HBsAg under a transmission electron microscope: the protein self assembles into [[virus-like particles]] HBsAg (also known as the Australia antigen) is the surface antigen of the hepatitis B virus (HBV). Its presence in blood indicates existing hepatitis B infection.

virion that lacks nucleic acid

protein family

glycoprotein spike on a viral capsid or viral envelope

Gp41 also known as glycoprotein 41 is a subunit of the envelope protein complex of retroviruses, including human immunodeficiency virus (HIV). Gp41 is a transmembrane protein that contains several sites within its ectodomain that are required for infection of host cells. As a result of its importance in host cell infection, it has also received much attention as a potential target for HIV vaccines.

InterPro Family

InterPro Family

thumb|Schematic overview of the hepatitis B virus particle. HBcAg is a constituent of the nucleocapsid core (green hexagon). thumb|The genome organisation of HBV. Some genes overlap. (ORF Core, at bottom left, encodes HBcAg.

Hemagglutinin of influenza virus