Studies of the N-terminal region of a parathyroid hormone-related peptide (1-36) analog: receptor subtype-selective agonists, antagonists, and photochemical cross-linking agents

Endocrinology. 1999 Nov;140(11):4972-81. doi: 10.1210/endo.140.11.7102.


The N-terminal regions of PTH and PTH-related peptide (PTHrP) are involved in receptor-mediated signaling and subtype selectivity. To better understand the molecular basis for these processes, we first prepared a series of [I5,W23,Y36]-PTHrP(1-36)NH2 analogs having stepwise deletions of residues 1-4 and characterized them with the human (h)PTH-1 and hPTH-2 receptor subtypes stably transfected in LLC-PK1 cells. Deletions beyond residue 2 caused progressive and severe losses in cAMP-signaling efficacy without dramatically diminishing receptor-binding affinity; consistent with this, [I5,W23]-PTHrP(5-36) was a potent antagonist for both PTH receptor subtypes. We then prepared and characterized photolabile analogs of [I5,W23,Y36]-PTHrP(1-36)NH2 that were singly modified with parabenzoyl-L-phenylalanine (Bpa) along the first six residues. These full-length analogs exhibited receptor subtype-selective agonism, antagonism, and photochemical cross-linking profiles. In particular, the [Bpa2]- and [Bpa4]-substituted analogs selectively antagonized and preferentially cross-linked to the PTH-1 receptor and PTH-2 receptor, respectively. These results demonstrate that the 1-5 region of [I5,W23]-PTHrP(1-36) is critical for activating the PTH-1 and PTH-2 receptors and suggest that the individual residues in this region play distinct roles in modulating the activation states of the two receptors. The cross-linking of both agonist and antagonist ligands to these PTH receptors lays the groundwork for identifying critical signaling determinants in the ligand binding pocket of the receptor.

Publication types

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

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Cell Line
  • Cross-Linking Reagents*
  • Humans
  • Kidney
  • Parathyroid Hormone / antagonists & inhibitors
  • Parathyroid Hormone-Related Protein*
  • Peptide Fragments / antagonists & inhibitors
  • Peptide Fragments / chemistry*
  • Peptide Fragments / metabolism
  • Peptide Fragments / pharmacology*
  • Phenylalanine / analogs & derivatives
  • Photochemistry
  • Proteins / chemistry*
  • Proteins / metabolism
  • Proteins / pharmacology*
  • Receptors, Parathyroid Hormone / agonists*
  • Receptors, Parathyroid Hormone / antagonists & inhibitors*
  • Receptors, Parathyroid Hormone / metabolism
  • Recombinant Proteins / metabolism
  • Structure-Activity Relationship
  • Swine
  • Transfection


  • Cross-Linking Reagents
  • Parathyroid Hormone
  • Parathyroid Hormone-Related Protein
  • Peptide Fragments
  • Proteins
  • Receptors, Parathyroid Hormone
  • Recombinant Proteins
  • parathyroid hormone-related peptide (1-36)
  • Phenylalanine
  • benzoylphenylalanine