Table 4.

Affinities of Bantag-1 and peptide #1 for mutants in first extracellular domain and third transmembrane in wild type BB₃, BB₃* and wild type BB₂ receptors (loss-of-affinity EC1 & TM3 combination point mutants).

	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	>30,000a	1.7 ± 0.1a
Combination point mutants in EC1
[H107K]	282 ± 21a	6.7 ± 0.3	195 ± 51a	8.6 ± 1.9
[E111D]	5.5 ± 1.1	6.4 ± 0.9	6.1 ± 0.3	9.5 ± 1.0
[G112R]	11.6 ± 2.1b	5.3 ± 0.4	16 ± 3b	5.6 ± 1.5
[H107K, G112R]	1,303 ± 113a	7.1 ± 0.6	378 ± 43a	9.8 ± 1.1
[H107K, E111D, G112R]	2,883 ± 98a	16 ± 2b	2,882 ± 98a	7.6 ± 1.3
Combination point mutants in TM3
[L123I]	20 ± 1a	10.1 ± 1.5b	>3,000	9.2 ± 3.6
[R127Q]	2,068 ± 258a	7.0 ± 0.7	1,331 ± 182a	5.9 ± 0.3
[L123I, R127Q]	>11,000a	7.0 ± 0.3	>15,000a	6.0 ± 1.4

^aP <0.0001 compared with BB₃ receptor;

^bP <0.05 compared with BB₃ receptor.

ND, Not done because Arg is already present in position 288 in BB₂ receptor.

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, 4, 5 and 6. Abbreviations: See in Fig. 1 and 2 legends.