Avian hepatitis B viruses: Molecular and cellular biology, phylogenesis, and host tropism

Figure 5 Dual topology of the viral surface protein L. The L protein is inserted into the ER membrane during synthesis with transmembrane domain 2 being inserted into the membrane. Half of the proteins then change their topology and insert the transmembrane domain 1 into the ER membrane. After this change and formation of the virus, L can exert its two basic functions; interaction with the nucleocapsid on the cytosolic preS domain and interaction with the host cell receptor on the surface of the viral particle.