Table 3.
Binding affinities of soluble type II receptors in ternary complexes
| Type I receptor (immobilized) | Ligand (analyte I) | Type II receptor (analyte 2) | |||
| ActR-II | ActR-IIB | BMPR-II | |||
| BMPR-IA | BMP2 | KD (eq), nM | 4,200 | 2,800 | 22,000 |
| BMPR-IB | SD | ± 714 | ± 357 | ± 6,160 | |
| BMPR-IA | GDF5 | KD (eq), nM | 20,000 | 2,900 | 32,000 |
| BMPR-IB | SD | ± 3,660 | ± 339 | ± 5,632 | |
| BMPR-IA | BMP7 | KD (eq), nM | 1,500 | 7,000 | 16,000 |
| BMPR-IB | SD | ± 130 | ± 1,015 | ± 2,592 | |
The data obtained from binding of type II receptor ectodomains (ECDs) as analyte to the preformed complexes were fitted by equilibrium dose response KD (eq). The data represent mean values of two measurements using at least six different type II receptor concentrations.
ActR = activin receptor; BMP(R) = bone morphogenic protein (receptor); GDF = growth and differentiation factor; SD = standard deviation.