TABLE 1

Kinetic parameters of [3H]-MLT, 2-[125I]-MLT, [125I]-SD6, [125I]-S70254, and [125I]-DIV880 with the hMT1 and hMT2 receptors at 37°C and at room temperature (RT)

Kinetic parameters (Kon, Koff, and half-life) of [3H]-MLT, 2-[125I]-MLT, [125I]-SD6, [125I]-S70254, and [125I]-DIV880 were measured on membranes from CHO-K1 cells expressing either hMT1 or hMT2 receptors. pKd was calculated as pKd = −log(Koff/Kon). Results are given as the mean ± S.E.M. for at least two experiments.

pKd(kinetics)Association Half-LifeDissociation Half-LifeKonKoff
37°CminminM−1.s−1s−1
 [3H]-MLTa
  hMT110.24 ± 0.053.0 ± 0.633.6 ± 2.96.10 × 1063.54 × 10−4
  hMT210.72 ± 0.022.6 ± 0.769.3 ± 8.27.37 × 1061.42 × 10−4
 2-[125I]-MLTa
  hMT110.94 ± 0.1120.5 ± 4.248.6 ± 12.52.20 × 1072.55 × 10−4
  hMT2—36.4 ± 4.1—1.23 × 107—
 [125I]-SD6
  hMT110.96 ± 0.025.18 ± 3.4332.25 ± 5.353.48 × 1073.79 × 10−4
  hMT210.36b17.89 ± 1.8035.04 ± 14.998.24 × 1063.63 × 10−4
 [125I]-S70254
  hMT1—————
  hMT210.97 ± 0.0712.72 ± 0.3947.42 ± 7.142.37 × 1072.56 × 10−4
 [125I]-DIV880
  hMT1—————
  hMT210.26 ± 0.1314.59 ± 1.4925.30 ± 4.408.85 × 1065.00 × 10−4
RT
 [3H]-MLTa
  hMT110.30 ± 0.052.7 ± 0.735.0 ± 2.16.75 × 1063.37 × 10−4
  hMT2—6.1 ± 3.8—3.78 × 106—
 2-[125I]-MLTa
  hMT110.60 ± 0.0648.6 ± 6.748.6 ± 6.79.58 × 1062.41 × 10−4
  hMT2—79.9 ± 9.9—5.60 × 106—
 [125I]-SD6
  hMT110.38 ± 0.0113.63 ± 9.2521.84 ± 3.231.34 × 1075.56 × 10−4
  hMT29.41b41.09 ± 5.809.63 ± 5.273.67 × 1061.41 × 10−3
 [125I]-S70254
  hMT1—————
  hMT210.45 ± 0.0818.42 ± 0.6821.37 ± 3.421.63 × 1075.87 × 10−4
 [125I]-DIV880
  hMT1—————
  hMT210.06 ± 0.2916.87 ± 7.2324.02 ± 7.507.90 × 1067.64 × 10−4

  • —, no binding.

  • ↵a Data already published by Legros et al. (2014).

  • ↵b No dissociation measurable at 20 min association time.