Figure 8.

Nicotine and CC4 promote the formation of pentameric receptors with two α3 and three β4 subunits. A–C, HeLa cells were transfected with cDNAs coding for α3 and for either the wild-type β4 (A,C) or for the export motif-deleted β4* subunit (B, see Fig. 6A). The transfected cells were incubated for 24 h either with or without 1 mm nicotine (A,B) or for 8 h with or without 10 μM MG132 (C). D, E, HeLa cells, transfected with the wild-type α3 and β4 subunits, were incubated for 8 h with CHX and then for 22 h with or without 1 mm nicotine (D) or 1 mm CC4 (E). For all panels, total cell lysates were analyzed by Western blotting; samples were run in duplicate on the same gel and probed separately with anti-α3 and β4 antibodies followed by incubation with an IR secondary antibody. The mean β4/α3 signal ratio, normalized to the ratio obtained in the absence of treatment, is shown. Statistical significance was evaluated by paired t test: n = 4 for A, B, D, E and = 3 for C. ***p < 0.001.