Table 1.
Radioligand binding and displacement kinetics of human TPα and human TP amino acid substitution mutants
| Receptor | Kda (nM) | 95% Confidence interval | Bmaxb (pM·mg−1) | Normoxic log Ki%c | Hypoxic log Ki%c |
|---|---|---|---|---|---|
| TPα wt | 3.79 | 2.80–4.78 | 783 ± 119 | −8.759 | −10.51 |
| Ser239A | 3.90 | 3.47–4.33 | 969 ± 48 | – | – |
| Ser324A | 2.23 | 1.81–2.65 | 1005 ± 61 | −11.43 | −11.69 |
| Ser329A | 3.80 | 2.21–5.08 | 968 ± 45 | −8.387 | −9.662 |
| Ser331A | 5.80 | 4.81–6.79 | 857 ± 41 | −8.389 | −9.082 |
Radioligand saturation binding kinetics assayed for human wild-type TPα and human TPα serine-to-alanine substitution mutants Ser239A, Ser324A, Ser329A and Ser331A, using labelled TP receptor antagonist [3H]-SQ29548; values from three experiments in duplicate.
Dissociation constant (Kd), expressing inverse of affinity of antagonist SQ29548 for the receptor. Boldface denotes receptor antagonist binding affinity differs from wild type (P < 0.05).
Maximum binding (Bmax) of the antagonist SQ29548 for TP receptor, usually expressed as pmol of the receptor mg-1 total membrane protein; mean ± SEM.
Competitive displacement kinetics under conditions of hypoxic and normoxic cell growth; saturating concentration of labelled antagonist [3H]-SQ29548, displaced with serial concentrations of cold agonist U46619. Ki is the equilibrium dissociation constants, calculated from concentration of agonist inhibiting 50% of antagonist binding. Boldface values differ from normoxic wild type Ki (P < 0.05).