Figure 4.
Concentration-response curves and constitutive activity of GluK2 mutants
(A) Representative whole-cell currents evoked by 1 s application of glutamate at two concentrations (10 mM, black traces; 30 μM, other colored traces) from recombinant receptors composed of the indicated subunits expressed in HEK293-T/17 cells.
(B) Peak current amplitudes at a range of glutamate concentrations were normalized to current amplitudes evoked by 10 mM glutamate. Logistic fits of the data yielded the EC50 data given in the text.
(C) Steady-state current amplitudes were normalized to peak currents over a range of glutamate concentrations before fitting with a logistic function.
(D) Representative traces showing the change in holding current after a 1 s application of 20 μM NASPM to cells expressing wild-type and mutant GluK2 KARs. Data are quantitated as the positive change in current upon application of NASPM in the graph. n = 4–6 recordings at each concentration. Error bars represent SEM. Statistical significance is denoted as ∗p < 0.05. p values are also given in the text. EC50, half-maximal effective concentration; KAR, kainate receptor; NASPM, 1-naphthyl acetyl spermine trihydrochloride; WT, wild-type.