FIG. 2.
Env glycoproteins in growth factor-independent clones of BER cells infected with passaged virus. Lysates from BER cells infected with wild-type SFFV (lane 1), BER cells infected with passaged virus 1218 (from which 11 clones analyzed in this blot were obtained by limiting dilution) (lane 2), clone 5S (lane 3), clone 4S (lane 4), clone 3S (lane 5), clone 2S (lane 6), clone 1S (lane 7), clone 6F (lane 8), clone 5F (lane 9), clone 4F (lane 10), clone 3F (lane 11), clone 2F (lane 12), and clone 1F (lane 13) were immunoprecipitated with anti-Env antibody, run on electrophoresis gels under reducing conditions, and transferred to nitrocellulose membranes. The membranes were again incubated with anti-Env antibody and then with [125I]protein A. The higher-Mr band at 70,000 to 90,000 occurs endogenously in the BaF3 cells (14).