FIG. 2.
Demonstration of M-M interaction. Genes coding for the mutant M proteins A2A3 and Δ18, the chimeric protein EAV M+9A, and the E protein were expressed in OST7-1 cells in various combinations, as indicated above each lane (−, absent), by using the vTF7-3 expression system. For the plasmid encoding protein A2A3, 5 μg was transfected, while for the plasmid encoding the E protein, 1 μg was used (A and B); 5 μg of the plasmid encoding the M protein Δ18 was used for panel A, and 1 μg was used for panel B, while 3 μg of the plasmid encoding the chimeric protein EAV M+9A was used for panel A and 1 or 5 μg was used for panel B. Cells were labeled for 2 (A) or 3 (B) h. Cell lysates were prepared and subjected to IP with either the anti-MHV serum (αMHV) or the monoclonal antibody to the amino terminus of M (αMN). When the E protein was coexpressed (B), culture media were also collected and processed for IP or for affinity isolation of VLPs. The affinity isolations were performed by using the monoclonal antibody anti-MN in the absence of detergents. The positions of the different proteins are indicated at the left, while the molecular mass markers are at the right. Only the relevant parts of the gels are shown.