FIG. 6.

Changes in intracellular pH retard proteolytic processing of Hendra F but not the SV5 F protein. Vero cells were transfected with pCAGGS-Hendra F (2 μg; A) or -SV5 F (1 μg; B) expression plasmids, metabolically labeled, and chased for 2 h in DMEM. Increasing concentrations of chloroquine were present in the starvation, label, and chase media. Cells were lysed, immunoprecipitated, and analyzed by SDS-15% PAGE and the STORM imaging system. The arrows on the right designate the positions of the F₀, F₁, and F₂ proteins. (C) pCAGGS-Hendra F-transfected Vero cells were metabolically labeled and chased as before in the absence (−) or presence (+) of 10 μM chloroquine, 10 mM NH₄Cl, 50 nM bafilomycin A1, or 10 nM concanamycin A. Chloroquine and NH₄Cl were present in the starvation, label, and chase media, and bafilomycin A1 and concanamycin A were present only in the chase medium. Samples were lysed, immunopreciptated, and either mock treated (−) or treated with 2 mU of Endo H (+) for 27 h at 37°C prior to analysis by SDS-10% PAGE and the STORM imaging system. Endo H-sensitive and -resistant F₀ (F₀^s and F_o^r) and F₁ (F₁^r) forms are indicated by the arrows on the right.