FIGURE 4.

α-Conotoxin TxIB has little or no activity at non-α6/α3β2β3 nAChR subtypes. nAChR subtypes were expressed as described under “Experimental Preocedures.” C indicates control responses to ACh. Oocytes were then exposed to 10 μm peptide for 5 min, followed by application of ACh. The peptide failed to block α3β2 (A), α6/α3β4 (B), and α3β4 (C) nAChRs. A representative response in a single oocyte is shown. D, Concentration-response of α-CTx TxIB on α6/α3β2β3 nAChRs and effect of 10 μM α-CTx TxIB on the other various nAChR subtypes. Values shown in the graph are mean ± S.E. from 3–5 separate oocytes. Dashed line shows concentration response curve of α6/α3β2β3 nAChRs for comparison.