TABLE 3

Affinities of peptides 4, 3, and 1 for wild-type BRS-3, BRS-3*, wild-type GRPR and TM2, second extracellular domain, TM3 point, or combination point mutants in BRS-3*

Results are calculated from data in Figure 3 as described under Materials and Methods. Point and point combination mutants refer to the BRS-3* receptor in which the indicated amino acid(s) of BRS-3* was replaced by the comparable amino acid of GRPR.

IC50
 Peptide 4
Peptide 3
Peptide 1
μM
BRS-3* 1.3 ± 0.1 0.08 ± 0.01 0.0022 ± 0.0001
GRPR >>100 2.8 ± 0.1 0.0009 ± 0.0001
e2-[GRPR]BRS-3* 33.1 ± 1.3a 0.34 ± 0.03a 0.0007 ± 0.0001
TM2 point mutant in BRS-3*
    [L98V]BRS-3* 1.8 ± 0.1 0.28 ± 0.01a 0.0030 ± 0.0001
    [V101A]BRS-3* 3.2 ± 0.1a 0.36 ± 0.01a 0.0030 ± 0.0001
Second extracellular domain point mutant in BRS-3*
    [T106S]BRS-3* 1.3 ± 0.1 0.16 ± 0.01a 0.0022 ± 0.0001
    [H107K]BRS-3* 33.1 ± 1.2a 0.35 ± 0.01a 0.0020 ± 0.0001
    [E111D]BRS-3* 1.9 ± 0.1 0.06 ± 0.01 0.0019 ± 0.0001
    [G112R]BRS-3* 4.8 ± 0.1a 0.04 ± 0.01 0.0028 ± 0.0004
TM3 point mutant in BRS-3*
    [V122L]BRS-3* 1.8 ± 0.1 0.04 ± 0.01 0.0028 ± 0.0001
    [L123I]BRS-3* 1.9 ± 0.1 0.08 ± 0.01 0.0022 ± 0.0002
    [S124P]BRS-3* 1.1 ± 0.1 0.03 ± 0.01 0.0019 ± 0.0001
Point combination mutants in BRS-3*
    [V101A, H107K]BRS-3* 34.7 ± 2.1a 0.0018 ± 0.0001
    [H107K, G112R]BRS-3* 36.3 ± 2.2a 0.0021 ± 0.0001
    [V101A, G112R]BRS-3* 15.1 ± 0.7ab 0.0053 ± 0.0001
    [V101A, H107K, G112R]BRS-3* >>100bc 0.0022 ± 0.0001
    [L98V, V101A]BRS-3* 0.36 ± 0.03a 0.0016 ± 0.0001
    [T106S, H107K]BRS-3* 0.42 ± 0.02a 0.0019 ± 0.0001
    [V101A, T106S, H107]BRS-3* 1.0 ± 0.1ad 0.0053 ± 0.0001
    [L98V, V101A, T106S, H107]BRS-3*
0.93 ± 0.05ad
0.0039 ± 0.0001

  • ↵ a P < 0.05 compared with BRS-3*.

  • ↵ b P < 0.0001 compared with single mutant [V101A] or [G112R].

  • ↵ c P < 0.0001 compared with [H107K], [V101A,H107K], or [H107K, G112R].

  • ↵ d P < 0.001 compared with [L98V, V101A], or [T106S, H107K].