TABLE 5.

Importance of the amino acid substitution in position 202 of GRPR for determining affinity for NMB

The affinities (IC₅₀) were determined as described in Table 1 and, for NMB, were from the dose-inhibition curves shown in Fig. 8. Studies were performed in transiently transfected Balb-3T3 cells as described in Table 1 legend. Significant increases in affinity from the wild type are shown. Values are means ± S.E.M. from at least four experiments, and in each experiment, each point was measured in duplicate.

	IC50
	NMB	Bn
	nM
WT NMBR	1.0 ± 0.2	4.5 ± 0.5
WT GRPR	115.1 ± 7.3	0.8 ± 0.1
[H202Q]GRPR	46.7 ± 4.8b	0.86 ± 0.15
[H202A]GRPR	56.1 ± 12.1b	0.80 ± 0.04
[H202F]GRPR	69.4 ± 7.9a	0.89 ± 0.15
[H202K]GRPR	167.2 ± 46.2	1.17 ± 0.24
[H202R]GRPR	98.9 ± 28.3	1.04 ± 0.23
[H202W]GRPR	92.3 ± 8.6	1.28 ± 0.08
[H202Y]GRPR	31.2 ± 5.8b	1.47 ± 0.34

^aa P < 0.02 vs WT GRPR for NMB.

^bb P < 0.005 vs WT GRPR for NMB.