Fig. 5.

OCLN does not bind soluble HCV E2 (sE2) directly. (A) Examples of production of human Fc (hFc) fusion proteins in 293T cells using a secretion system. Fusion proteins could be readily detected by western blotting using an anti-human secondary antibody in either cell lysates or supernatants. Notably, the OCLN-EL1-hFc expression is relatively low. To ensure the specific detection, a stop codon was introduced between the EL and hFc, which results in the production of proteins without hFc tag. (B) Purified Fc fusion proteins were bound to protein G beads first and then incubated with sE2. After wash, bound protein was eluted and immunoblotted with anti-E2 mAb, striped, and reprobed with anti-hFc. Only the hCD81 large extracellular loop (hCD81-LEL-hFc) could bind sE2. CLDN1-EL1(E48K)-hFc harbors an E→K mutation at residue 48.