Figure 1.

Overexpression of G_iα1 inhibits receptor-mediated endocytosis. (A) Immunoblot of COS-7 cells infected with adenoviruses encoding G_iα1, β₁, γ₂, and/or β-galactosidase. Antiserum P960 recognizes G_iα1 and several other G_α proteins (31), whereas antiserum B600 recognizes β subunits (20). Hela cells (B) and CV1 cells (C and D) were grown in 35-mm 6-well culture dishes for 16 h before infection with the indicated viruses. Cell were exposed to 150 moi (multiplicity of infection) units of total virus (50 moi of virus encoding each indicated G protein subunit, the remainder encoding β-galactosidase). Cells were approximately 80% confluent at the time of infection. Cells were assayed 48 h later for uptake of ¹²⁵I-transferrin (B) or ¹²⁵I-LDL (C and D). Error bars represent standard deviations (n = 3).