Table 2

Affinities of NMB, Bn, and [d-Tyr⁶,β-Ala¹¹,Phe¹³,Nle¹⁴]Bn-(6–14) for wild-type GRPR, NMBR, and GRPR EC3 region of single or double gain-of-affinity mutants for NMB

Affinities of NMB, Bn, and [d-Phe⁶,ß-Ala¹¹,Phe¹³,Nle¹⁴]Bn-(6–14) for wild-type GRP or NMB peptide and for selected single and double EC3 amino acid(s) mutant GRP receptors (gain-of-affinity). All mutants were from the EC3 regions (Fig. 4), with the exception of the [S215I]GRPR mutants, which contains a substitution of a serine by isoleucine in the upper TM5 (Fig. 4). The terminology [D181E]GRPR, for example, indicates that Asp, which occurs in position 181 of GRPR (Fig. 4) was substituted by Glu, which occurs in the comparable position in NMBR (Fig. 4). The affinities (IC₅₀) were measured as measured by competitive displacement of 50 pM ¹²⁵I-[Tyr⁴]Bn by NMB or Bn in transiently transfected Balb-3T3 cells. Cells were transfected as described under Materials and Methods. These data were calculated from the NMB dose-inhibitation curve for selected mutants shown in Fig. 5. Values are means ± S.E.M. from at least four experiments, and in each experiment, each point was determined in duplicate.