TABLE 1

Potency and efficacy of PTH/PTHrP peptides for stimulation of cAMP accumulation, β-arrestin recruitment, IP1 accumulation, ERK1/2 phosphorylation, and receptor internalization

EC50 values represent the mean ± S.E.M. of the indicated number of independent determinations in which 8–10 different assay concentrations were tested in either duplicate or triplicate. Agonist efficacy is based on the maximal response of PTH(1-34) obtained in the same assay plate. EC50 values were determined as described in Materials and Methods.

PeptidecAMP EC50IP1 EC50β-Arrestin EC50ERK1/2 EC50Internalization
Efficacy (% PTH)Efficacy (% PTH)Efficacy (% PTH)Efficacy (% PTH)Efficacy (% PTH)
nM nM nM nM nM
Full-Length PTH/PTHrP Peptide Analogs
 PTH(1-34)0.6 ± 0.1 (52)b,d30 ± 4 (8)c,e1.3 ± 0.1 (36)d16 ± 3 (18)5.0 ± 0.8 (12)d
100100100100100
 PTHrP(1-34)2.0 ± 0.7 (3)*b51 ± 18 (3)e1.9 ± 1.2 (3)19 ± 8 (5)3.0 ± 0.5 (3)
100 ± 4d103 ± 7d,e95 ± 583 ± 4**110 ± 8**
 PTH(1-37)0.6 ± 0.1 (3)ND4.7 ± 1.4 (4)*13 ± 6 (3)ND
105 ± 393 ± 5111 ± 13
 PTHrP(1-37)0.4 ± 0.1 (4)dND0.9 ± 0.2 (4)d10 ± 3 (4)ND
103 ± 3d100 ± 1d74 ± 3**a,c
 [Bpa1]PTHrP(1-36)1.0 ± 0.1 (3)c>10,000 (2)7.3 ± 1.0 (3)>10,000 (2)>10,000 (3)
102 ± 3c50 ± 6**
 [Trp1]PTHrP(1-36)2.1 ± 0.7(3)*e>10,000 (2)15 ± 9 (3)*e>10,000 (2)103 ± 15 (3)*
110 ± 4c,e42 ± 5**48 ± 10**
 [Tyr1]PTH(1-34)0.7 ± 0.3 (4)c,e>10,000 (2)27 ± 4 (3)*e>10,000 (2)104 ± 29 (3)*
100 ± 6c,e56 ± 7**75 ± 4**
 [Nle8,18,Tyr34]PTH(1-34)0.4 ± 0.1 (3)b56 ± 38 (2)e3.4 ± 0.7 (3)b18 ± 2 (3)5.4 ± 0.5 (2)
99 ± 187 ± 993 ± 368 ± 11107±2
N-Terminal Truncated PTH/PTHrP Peptide Analogs
 PTH(2-38)0.7±0.1 (3)c>10,000 (2)79 ± 19 (4)*>10,000 (4)>10,000 (2)
99±2c12 ± 0.6**
 PTH(3-34)173±38 (4) *>10,000 (2)>10,000 (3)>10,000 (2)>10,000 (2)
53±7**
 [Nle8,18,Tyr34]PTH(3-34)NH256±10 (3)*ND>10,000 (3)>10,000 (2)ND
43±3**
 [D-Trp12,Tyr34]PTH(7-34)NH2>10,000 (2)ND>10,000 (3)>10,000 (5)>10,000 (2)
 [Nle8,18,Tyr34]PTH(7-34)>10,000 (2)ND>10,000 (2)>10,000 (2)ND
 [Tyr34]PTH(7-34)NH2>10,000 (2)ND>10,000 (2)>10,000 (2)ND
 PTHrP(7-34)NH2>10,000 (2)ND>10,000 (3)>10,000 (2)>10,000 (2)
 PTH(7-34)NDND>10,000 (1)>10,000 (2)>10,000 (1)
 [Asn10,Leu11,D-Trp12] PTHrP(7-34)NH2>10,000 (2)ND>10,000 (2)>10,000 (2)ND
C-Terminal Truncated PTH/PTHrP Peptide Analogs
 PTH(1-31)1.3 ± 0.6 (3)33 ± 10 (2)3.6 ± 0.5 (3)35 ± 5 (4)6.4 ± 1.9 (2)
108 ± 888 ± 291 ± 1**85 ± 16100 ± 2
 PTH(1-31)NH20.6 ± 0.3 (4)dND4.7 ± 0.6 (4)*d9.55 ± 0.35 (2)ND
96 ± 1093 ± 5123 ± 8
 (Cyclo(Glu22-Lys26),Leu27] PTH(1-31)NH20.8 ± 0.1 (3)23 ± 13 (2)0.8 ± 0.2 (3)11 ± 3 (2)0.51 ± 0.03 (2)
105 ± 2100 ± 3110 ± 796 ± 1175 ± 11
 PTH(1-28)2.9 ± 0.7 (5)*b1529 ± 375 (2)*d,e**43 ± 1 (2)*b98 ± 14 (3)*268 ± 45(4)*
105 ± 3d99 ± 394 ± 1851 ± 13**e140 ± 6**
 MPTH(1-28)0.4 ± 0.2 (2)b,d10 ± 1 (2)de0.4 ± 0.1 (2)b,d7 ± 3 (2)1.1 ± 0.3 (3)
101 ± 12e97 ± 3e108 ± 8e110 ± 2e63 ± 6**
 [Gly1Arg19]PTH(1-28)0.9 ± 0.2 (2)b,e2692 ± 99 (2)*d77 ± 5 (2)*b53 ± 31 (2)e680 ± 148 (3)*
98 ± 2106 ± 882 ± 1249 ± 18e140 ± 14**
 ZP23076.2 ± 1.2 (5)*b5,327 ± 2044 (2)*d107 ± 4 (3)*b213 ± 69* (3)1,714 ± 185 (3)*
113 ± 3*85 ± 191 ± 653 ± 12**152 ± 4**
 PTHrP(1-16)>10,000 (1)>10,000 (1)>10,000 (2)>10,000 (2)>10,000 (2)
 MPTH(1-14)0.5 ± 0.1 (4)b,e1,353 ± 349 (2)*d,e21 ± 3 (3)*b136 ± 54* (3)234 ± 9 (3)*
104 ± 2d,e87 ± 2e90 ± 13e60 ± 10*e151 ± 2**
 [Aib1,3,Nle8, Gln10,Har11] PTH(1-11)NH217 ± 4 (4)*>10,000 (2)587 ± 235* (4)>10,000 (2)>10,000 (2)
101 ± 191 ± 1**
  • ND, not determined.

  • a Statistically significant difference (P < 0.05) in agonist potency and/or efficacy compared to the agonist potency and/or efficacy obtained in the cAMP accumulation assay as determined by a one-way analysis of variance followed by a Tukey's posttest.

  • b Statistically significant difference (P < 0.05) in agonist potency and/or efficacy compared to the agonist potency and/or efficacy obtained in the IP1 accumulation assay as determined by a one-way analysis of variance followed by a Tukey's posttest.

  • c Statistically significant difference (P < 0.05) in agonist potency and/or efficacy compared to the agonist potency and/or efficacy obtained in the β-arrestin recruitment assay as determined by a one-way analysis of variance followed by a Tukey's posttest.

  • d Statistically significant difference (P < 0.05) in agonist potency and/or efficacy compared to the agonist potency and/or efficacy obtained in the ERK1/2 phosphorylation assay as determined by a one-way analysis of variance followed by a Tukey's posttest.

  • e Statistically significantly difference (P < 0.05) in the agonist potency and/or efficacy compared to the agonist potency and/or efficacy obtained in the receptor internalization assay as determined by a one-way analysis of variance followed by a Tukey's posttest.

  • * Statistically significant difference (P < 0.001) in agonist potency compared with PTH(1-34), as calculated by unpaired two-tailed Student’s t test.

  • ** Statistically significant difference (P < 0.05) in agonist efficacy, compared with PTH(1-34), as calculated by a paired one-tailed Student’s t test.