Enhanced activity in parathyroid hormone-(1-14) and -(1-11): novel peptides for probing ligand-receptor interactions

Endocrinology. 2001 Jul;142(7):3068-74. doi: 10.1210/endo.142.7.8253.


The amino-terminal portion of PTH is critical for PTH-1 receptor (P1Rc) activation. In exploring this component of the ligand receptor interaction, we recently showed that the agonist potency of the weakly active PTH-(1-14)NH(2) peptide can be enhanced by natural amino acid substitutions at several positions, including position 11 (normally leucine). Here we show that the potency of PTH-(1-14)NH(2) can be enhanced by using nonnatural amino acids that increase the length and polarizability of the position 11 side-chain. Thus, in LLC-PK(1) cells stably expressing high levels of the human P1Rc, [homoarginine([Har)(11)]PTH-(1-14)NH(2) was 30-fold more potent for cAMP production than was native PTH-(1-14)NH(2). Combining the homoarginine-11 substitution with other recently identified activity-enhancing substitutions yielded [Ala(3,12),Gln(10),Har(11),Trp(14)]PTH-(1-14)NH(2), which was 1500-fold more potent than PTH-(1-14)NH(2) (EC(50) = 0.12 +/- 0.04 and 190 +/- 20 microM, respectively) and only 63-fold less potent than PTH-(1-34) (EC(50) = 1.9 +/- 0.5 nM). The even shorter analog [Ala(3),Gln(10),Har(11)]PTH-(1-11)NH(2) was also a full cAMP agonist (EC(50) = 3.1 +/- 1.5 microM). Receptor mutations at Phe(184) and Leu(187) located near the boundary of the amino-terminal domain and transmembrane domain-1 severely impaired responsiveness to the PTH-(1-11) analog. Overall, these studies demonstrate that PTH analogs of only 11 amino acids are sufficient for activation of the PTH-1 receptor through interaction with its juxtamembrane region.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Binding, Competitive
  • COS Cells
  • Cyclic AMP / biosynthesis
  • Humans
  • LLC-PK1 Cells
  • Ligands
  • Parathyroid Hormone / genetics
  • Parathyroid Hormone / metabolism
  • Parathyroid Hormone / pharmacology*
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Peptide Fragments / pharmacology*
  • Receptors, Parathyroid Hormone / drug effects*
  • Receptors, Parathyroid Hormone / metabolism*
  • Structure-Activity Relationship
  • Swine
  • Tumor Cells, Cultured
  • Type C Phospholipases / metabolism


  • Ligands
  • Parathyroid Hormone
  • Peptide Fragments
  • Receptors, Parathyroid Hormone
  • parathyroid hormone (1-11)amide, Ala(3)-Gln(10)-Har(11)-
  • parathyroid hormone (1-14)amide
  • Cyclic AMP
  • Type C Phospholipases