TABLE 1

pKI values for AM and CGRP variants determined by FP peptide-binding assay

PeptideaMBP-RAMP1-CLRECD pKI ± S.E.M. (n)MBP-RAMP2- CLR ECD pKI ± S.E.M. (n)Selectivity, RAMP1 (R1) vs. RAMP2 (R2) Δlog (95% CI)b
AM(22–52)<4.3 (2)c4.63 ± 0.10 (3)R2
AM(37–52)<4.3 (3)4.72 ± 0.07 (3)R2
Q50F4.97 ± 0.07 (3)5.67 ± 0.05 (3)−0.70 (−0.94 to −0.46)**
Q50W6.12 ± 0.02 (3)6.18 ± 0.12 (3)−0.06 (−0.41 to +0.28)
K46L/Q50W7.17 ± 0.03 (3)5.75 ± 0.03 (3)+1.42 (+1.30 to +1.54)***
K46L/Q50W/Y52F7.39 ± 0.11 (3)<4.3 (3)R1
S45W/Q50W7.40 ± 0.05 (3)7.19 ± 0.06 (3)+0.21 (−0.01 to +0.42)
S45W/K46L/Q50W8.14 ± 0.10 (3)6.69 ± 0.08 (3)+1.46 (+1.10 to +1.82)***
S45W/K46L/Q50W/Y52F (AMmut)8.47 ± 0.21 (3)5.13 ± 0.03 (3)+3.33 (+2.76 to +3.91)***
S45W/K46M/Q50W/Y52F8.10 ± 0.16 (3)5.08 ± 0.03 (3)+3.02 (+2.57 to +3.47)***
CGRP(8–37)<4.3 (3)NBD (2)R1
CGRP(27-37) N31D/S34P/K35F (CGRPmut)7.48 ± 0.12 (3)<4.3 (3)R1
N31D/S34P/K35W8.12 ± 0.11 (3)<4.3 (3)R1
N31D/S34P/K35F/A36S8.24 ± 0.04 (3)4.97 ± 0.10 (3)+3.26 (+2.95 to +3.58)***
N31D/S34P/K35W/A36S8.93 ± 0.14 (3)5.64 ± 0.13 (3)+3.29 (+2.76 to +3.82)***
N31D/S34P/K35W/A36S/F37Y8.61 ± 0.24 (3)6.33 ± 0.11 (3)+2.28 (+1.53 to +3.02)**
  • CI, confidence interval; NBD, no binding detected.

  • a All variants were in the AM(37–52) or CGRP(27–37) scaffolds.

  • b Statistical comparisons of RAMP1- and RAMP2-CLR ECD data were performed using unpaired Student’s t test.

  • c <4.3 indicates weak binding was detected at maximum concentration used but pKI was not determined.

  • ** P < 0.01; ***P < 0.001.