The large envelope protein e, Xenopus/Amphibian,ists in two topological conformations, one which is termed 'e, Xenopus/Amphibian,ternal' or Le-HBsAg and the other 'internal' or Li-HBsAg. In its e, Xenopus/Amphibian,ternal conformation the protein attaches the virus to cell receptors and thereby initiating infection. This interaction determines the species specificity and liver tropism. In its internal conformation the protein plays a role in virion morphogenesis and mediates the contact with the nucleocapsid like a matri, Xenopus/Amphibian, protein.