Figure 1.

HCV genome organization (top) and polyprotein processing (bottom). HCV encodes a single polyprotein with the structural proteins (S) and the nonstructural proteins (NS) present in the N-terminal one-third and the C-terminal two-third of the polyprotein, respectively. The polyprotein processing and the location of the 10 proteins relative to the endoplasmic reticulum membrane are schematically represented. Scissors indicate cleavages by a host signal peptidase. Arrows indicate NS2-3 and NS3-4A cleavages. The intramembrane arrow indicates cleavage by a host signal peptide peptidase (SPP). The transmembrane domains of E1 and E2 are shown after signal-peptidase cleavage and reorientation of their C-terminus. In addition, the precleavage topology of the transmembrane domains of E1 and E2 is shown in light grey.