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. 2016 Jun 23;11(6):e0158032. doi: 10.1371/journal.pone.0158032

Fig 7. β2V287L increased the ACh sensitivity of α4β2 nAChRs in N2a cells but reduced maximum response.

Fig 7

The α4 subunit was labeled with an enhanced green fluorescent protein (eGFP) tag to facilitate the identification of cells expressing α4β2 nAChRs. The cells were voltage-clamped at -60 mV in whole-cell mode. a. Normalized ACh concentration-response relations for the α4-eGFPβ2 (filled circles) or α4-eGFPβ2V287L receptors (open circles). The α4-eGFPβ2 and α4-eGFPβ2V287L ACh responses were normalized to the peak 100 μM response. The α4-eGFPβ2 symbol at 100 μM ACh is obscured by that for α4-eGFPβ2V287L. The dashed (α4-eGFPβ2V287L) and solid lines (α4-eGFPβ2) are fits to the three-parameter Hill equation (see text for values of fitted parameters). b-c. Superimposed traces of α4-eGFPβ2 (black) and α4-eGFPβ2V287L (red) responses to 300 ms applications of 1 (b) and 100 μM ACh (c). At 1 μM ACh, the α4-eGFPβ2V287L response was larger than α4-eGFPβ2 response. At 100 μM ACh, it was smaller. Downward arrows denote the onset of a 300 ms ACh application.