Fig. 6.

Grb2 associates with the AChR in situ. AChRs were isolated from solubilizedTorpedo membranes by α-bungarotoxin–Sepharose, were eluted in SDS, and were resolved by SDS-PAGE. Coomassie staining of the preparation shows the four subunits of the AChR: α, ∼40 kDa; β, ∼50 kDa; γ, ∼60 kDa; and δ, ∼65 kDa. Preincubation with excess α-bungarotoxin (25 μm) prevents binding of AChR to the toxin–Sepharose (left). Immunoblotting the samples with anti-Grb2 antibodies reveals that Grb2 specifically copurifies with the AChR (right).