Table 2.
Affinities of Bantag-1 and peptide #1 for wild type BB3, BB3*, wild type BB2, and extracellular chimeric BB3 and BB2 receptors (loss- and gain-of-affinity).
|
Ki (nM)
|
||||
|---|---|---|---|---|
| BB3* | Wild type | |||
|
|
||||
| Receptor | Bantag-1 | Peptide #1 | Bantag-1 | Peptide #1 |
| BB3 | 5.2 ± 0.5 | 4.9 ± 0.8 | 5.6 ± 0.4 | 8.1 ± 1.0 |
| BB2 | ND | ND | >30,000 a | 1.7 ± 0.1a |
| Extracellular chimeras (loss-of-affinity) | ||||
| (e1-BB2) BB3 | 1,962 ± 432a | 9.7 ± 1.6 | N.B. | N.B. |
| (e2-BB2) BB3 | 120 ± 26a | 8.1 ± 2.9 | N.B. | N.B. |
| (e3-BB2) BB3 | 5.9 ± 0.7 b | 6.3 ± 1.2 b | 5.9 ± 0.7 | 6.3 ± 1.2 |
| Extracellular chimeras (gain-of-affinity) | ||||
| (e1-BB3) BB2 | ND | ND | >6,000 | 1.8 ± 0.2 |
| (e2-BB3) BB2 | ND | ND | >30,000 | 3.8 ± 1.0 |
| (e3-BB3) BB2 | ND | ND | >30,000 | 3.6 ± 0.2 |
a
P <0.0001 compared to BB3 receptor.
ND, Not done because Arg is already present in position 288 in BB2 receptor.
N.B, no detectable binding above background.
CHOP cells type were incubated with 50 pM 125I-[D-Tyr6, β-Ala11, Phe13, Nle14]Bn-(6–14) for 60 minutes at 21°C and binding was determined as described in Materials and Methods. In each experiment each value was determined in duplicate, and values given are means and S.E.M. from at least three separate experiments. Data are calculated from dose-inhibition curves shown in Fig. 1–3. Abbreviations: See in Fig. 1 and 2 legends.