Role of BiP in the action of overexpressed Sec63.

<p><b>A.</b> HuH-7 cells were cotransfected with HBV.S (left panels) or CD63 (right panels) in combination with control DNA or the Myc-tagged wt Sec63 or mutant Sec63ΔHPD at a 1∶3 DNA ratio, respectively. In case of HBV.S, cellular lysates were subjected to anti-Myc (top), anti- β-actin (middle), and anti-HA (bottom) WB. Relative HBV.S expression values ± SD (<i>n</i> = 4) were determined as in Fig. 1. In case of CD63, lysates were probed by anti-β-actin (top) and anti-HA (bottom) WB. <b>B.</b> For cotransfections with HBV.S, control DNA, Myc-tagged Sec63, and FLAG-tagged BiP were used as a 1∶3 or 1∶3∶3 DNA ratio, respectively. Cell extracts were probed by WB with antibodies against Myc (top), FLAG (top middle), or HA (bottom). Uniformity of sample loading is shown by a band cross-reacting with the HA antibody (load; bottom middle). Relative HBV.S expression values ± SD (<i>n</i> = 2) were determined as in Fig. 1.