Table 3

Parameters of fitting procedures

Parameterα1α1K104Aα1F108Aα1T112A
Taurine(5)(5)(4)(6)
 K a [mM]1.79  ± 0.50.68  ± 0.090.61  ± 0.110.8  ± 0.3
 K b [mM]1.38  ± 2.51.32  ± 0.32.63  ± 0.7010.4  ± 5.9
 n 2.5  ± 0.62.4  ± 0.32.1  ± 0.142.5  ± 0.2
 SS10.11  ± 0.040.14  ± 0.020.3  ± 0.060.34  ± 0.15
 SS20.11  ± 0.050.14  ± 0.050.4  ± 0.090.28  ± 0.10
β-ABA(5)(10)(2)(3)
 K a [mM]7.5  ± 2.32.72  ± 0.441.56  ± 0.849.1  ± 2.4
 K b [mM]2.07  ± 0.44.49  ± 0.592.44  ± 1.4617.7  ± 1.8
 n 2.6  ± 0.52.7  ± 0.282.2  ± 0.72.0  ± 0.1
 SS10.005  ± 0.0040.12  ± 0.020.16  ± 0.020.3  ± 0.1
 SS20.005  ± 0.0040.12  ± 0.030.18  ± 0.040.23  ± 0.01
β-AIBA(5)(3)
 K a [mM]15.8  ± 7.926.3  ± 20.7n.d.n.d.
 K b [mM]4.6  ± 1.610.9  ± 4.5n.d.n.d.
 n 2.4  ± 0.42.9  ± 0.6n.d.n.d.
 SS10.005  ± 0.0020.04  ± 0.03n.d.n.d.
 SS20.011  ± 0.0040.02  ± 0.02n.d.n.d.

The data of the concentration-effect relations of the partial agonists taurine, β-ABA, and β-AIBA were fitted by eq. 3 (see text) using a least squares procedure. The equivalents of agonistic and antagonistic binding are described by K a andK b, respectively (mean ± S.E.M.); nis the Hill coefficient. The numbers of experiments are given in brackets. The quality of fits was determined by the sum of squares (SS1). In addition, fits were designed by the logistic function 1 (seeMaterials and Methods); their quality is represented by SS2. All values of SS1 and SS2 are multiplied by hundred. Values for the wt α1 subunit GlyR were calculated from the data given in Schmieden and Betz, 1996.

    • n.d., not determined.