FIG. 4.

Membrane topology of SARS-CoV and MHV nsp3 and nsp6. vTF7-3-infected OST7-1 cells were transfected with constructs encoding the proteins indicated at the left. The cells were fixed at 6 h p.i. and permeabilized with Triton X-100 (left two columns) or digitonin (right two columns). Immunofluorescence analysis was performed with antibodies against the C-terminal (C-term.) tag, anti-M_c for M_m and anti-HA for the nsps (first and third columns), or against the N-terminal (N-term.) tag, J1.3 (anti-M_N, second and fourth columns).