Table 1 Mutational analyses identifying the glutamate binding pocket at the α1 + /β2- interface of the α1β2γ2 GABAAR

From: Glutamate and GABAA receptor crosstalk mediates homeostatic regulation of neuronal excitation in the mammalian brain

a. Effects on glutamate potentiation by individual mutation of putative α1 or β2 amino acid residues forming the loop C pocket (P1; see Supplementary Fig. S2b)

 

Relative potentiation

EC50 (μM)

Hill Slope

Imax (nA)

N

α1 β2 γ2 WT

100.0%

10.4 ± 1.1

1.41 ± 0.14

1.2 ± 0.4

6

α1S158A β2 γ2

106.9 ± 39.8%

6.4 ± 1.1

1.50 ± 0.21

1.3 ± 0.5

3

α1Y159A β2 γ2

90.8 ± 26.7%

7.9 ± 1.1

1.45 ± 0.25

1.1 ± 0.5

3

α1S205A β2 γ2

113.1 ± 33.0%

10.2 ± 1.0

1.16 ± 0.43

2.3 ± 1.1

3

α1T206A β2 γ2

129.3 ± 61.7%

8.6 ± 1.3

1.50 ± 0.45

1.9 ± 0.8

3

α1E208A β2 γ2

90.9 ± 28.7%

9.4 ± 1.3

1.46 ± 0.53

1.8 ± 0.8

3

α1 β2G126A γ2

n/a

152.7 ± 1.1

2.28 ± 0.74

1.3 ± 0.4

3

α1 β2Q63A γ2

n/a

163.4 ± 1.2

2.09 ± 0.93

1.0 ± 0.5

3

α1H101A β2 γ2

n/a

120.0 ± 1.2

1.45 ± 0.52

0.9 ± 0.5

3

α1F99A β2 γ2

96.4 ± 23.0%

8.9 ± 1.3

1.10 ± 0.27

1.0 ± 0.7

3

α1 β2V177A γ2

89.5 ± 28.3%

8.7 ± 1.1

1.12 ± 0.37

1.7 ± 0.9

3

α1 β2Y61A γ2

n/a

176.5 ± 1.2

2.91 ± 1.30

1.0 ± 0.5

3

b. Effects on glutamate potentiation by individual mutation of putative α1 or β2 amino acid residues forming the pocket below loop C (P2; see Supplementary Fig. S2b, c)

 

Relative potentiation

EC50 (μM)

Hill Slope

Imax (nA)

N

α1K104D β2 γ2

8.0 ± 10.7%

11.0 ± 1.1

1.70 ± 0.17

2.3 ± 0.7

6

α1E137G β2 γ2

2.1 ± 7.7%

11.9 ± 1.0

1.35 ± 0.03

1.2 ± 0.3

6

α1K155D β2 γ2

9.0 ± 10.0%

8.5 ± 1.1

1.39 ± 0.21

1.3 ± 0.5

6

α1 β2E181G γ2

1.6 ± 11.6%

10.0 ± 1.1

1.59 ± 0.14

1.1 ± 0.2

6

α1 β2 I180A γ2

18.8 ± 12.9%

8.0 ± 1.2

1.42 ± 0.27

1.7 ± 0.4

6

  1. HEK cells were transiently co-transfected with either wild or mutant α1, β2, and γ2 subunits. Whole-cell recordings were performed with a Cl-based recording pipette at a holding membrane potential of −60mV, and GABA currents were evoked with fast perfusion of GABA (1 µM; 3 s). Glutamate potentiation were determined by co-applications of glutamate 100 μM; and normalized to that observed in HEK cells expressing wild-type α1β2γ2 receptors
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