Characterization of a Guanosine-Nucleotide-Binding-Protein-Coupled Receptor for Pituitary Adenylate-Cyclase-Activating Polypeptide on Plasma Membranes From Rat Brain

Eur J Biochem. 1991 Dec 18;202(3):951-8. doi: 10.1111/j.1432-1033.1991.tb16455.x.

Abstract

Pituitary adenylate-cyclase-activating polypeptide (PACAP), a novel brain-gut hormone, was isolated from ovine hypothalami and represents the latest mammalian member of the secretin-glucagon peptide family. PACAP exists in two C-terminally amidated molecular forms, PACAP(1-27) and PACAP(1-38), comprising 27 or 38 amino acid residues, respectively. In order to identify a specific receptor for PACAP, we studied binding of 125I-labelled PACAP(1-27) to plasma membranes from rat brain. We identified a single high-affinity binding site (Kd, 340 pM and Bmax, 3.34 pmol/mg), specific for synthetic PACAP(1-38) and PACAP(1-27). Hormone binding was reversible and time, protein and temperature dependent. In contrast, neither the analogues PACAP(1-23), PACAP(18-38) and PACAP(3-25), nor vasoactive intestinal peptide (VIP), secretin and growth-hormone-releasing factor (GRF) revealed significant binding at concentrations up to 1 microM. A specific receptor protein, with an apparent molecular mass of 60 kDa, was identified by means of affinity cross-linking with disuccinimidyl suberate (DSS) and ethylene glycol disuccinimidyl suberate (EGS). PACAP receptors are associated with a GTP-binding protein as determined by the influence of different nucleotides on PACAP binding. PACAP-binding activity was solubilized with the detergents 3-[(3-cholamidopropyl)dimethylammonio]2-hydroxy-1-propane sulfonate (Chapso) or Triton X-100 and was characterized as a high-molecular-mass receptor complex (400 kDa) by non-reducing size-exclusion chromatography on Sepharose CL-6B. These data imply the following: high-affinity PACAP receptors are expressed abundantly on rat-brain plasma membranes; PACAP receptors are specific for PACAP and show no affinity for VIP, secretin and GRF; the PACAP receptor molecule has an apparent molecular mass of 60 kDa; the PACAP receptor complex is associated with a GTP-binding protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine Nucleotides / pharmacology
  • Adenylyl Cyclases / metabolism*
  • Animals
  • Binding, Competitive
  • Brain / metabolism*
  • Cell Membrane / metabolism
  • Cross-Linking Reagents
  • GTP-Binding Proteins / metabolism*
  • Guanine Nucleotides / pharmacology
  • Kinetics
  • Neuropeptides / metabolism*
  • Peptides / chemical synthesis
  • Peptides / pharmacology
  • Pituitary Adenylate Cyclase-Activating Polypeptide
  • Rats
  • Receptors, Cell Surface / drug effects
  • Receptors, Cell Surface / metabolism*
  • Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
  • Receptors, Pituitary Hormone*
  • Vasoactive Intestinal Peptide / pharmacology

Substances

  • Adcyap1 protein, rat
  • Adenine Nucleotides
  • Cross-Linking Reagents
  • Guanine Nucleotides
  • Neuropeptides
  • Peptides
  • Pituitary Adenylate Cyclase-Activating Polypeptide
  • Receptors, Cell Surface
  • Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
  • Receptors, Pituitary Hormone
  • Vasoactive Intestinal Peptide
  • GTP-Binding Proteins
  • Adenylyl Cyclases