TABLE 4

Correlations between agonist affinities in the agonist competition binding assay and potencies for GTPase activation as well as correlation between potencies in the GTPase- and AC assay The Kih and Kil values were taken from Table 1. The EC50 values for GTPase activation were taken from Table 2, and the EC50 values for AC activation were taken from Table 3. Coefficients of the various parameters were calculated for the four catecholamines studied.

Ligand
β1AR-GsαL
β1AR-GsαS
β2AR-GsαL
β2AR-GsαS
Kih/EC50 GTPase
   ISO 0.0625 0.0313 0.0460 0.0571
   EPI 0.2692 0.1615 0.0750 0.0201
   NE 0.0600 0.0883 0.0377 0.0297
   DOP 0.4455 0.0163 0.0131 0.0027
Kil/EC50 GTPase
   ISO 6.5 4.7 9.4 4.3
   EPI 10.8 12. 20.0 4.7
   NE 11.5 6.5 21.5 3.3
   DOP 17.3 10.9 5.8 1.1
EC50 GTPase/EC50 AC
   ISO 0.55 2.00 0.67 0.78
   EPI 1.71 1.53 0.28 1.16
   NE 0.55 2.14 0.57 0.59
   DOP
0.61
0.68
1.07
1.21