Receptor Activity-modifying Proteins 2 and 3 Generate Adrenomedullin Receptor Subtypes with Distinct Molecular Properties

J Biol Chem. 2016 May 27;291(22):11657-75. doi: 10.1074/jbc.M115.688218. Epub 2016 Mar 24.


Adrenomedullin (AM) is a peptide hormone with numerous effects in the vascular systems. AM signals through the AM1 and AM2 receptors formed by the obligate heterodimerization of a G protein-coupled receptor, the calcitonin receptor-like receptor (CLR), and receptor activity-modifying proteins 2 and 3 (RAMP2 and RAMP3), respectively. These different CLR-RAMP interactions yield discrete receptor pharmacology and physiological effects. The effective design of therapeutics that target the individual AM receptors is dependent on understanding the molecular details of the effects of RAMPs on CLR. To understand the role of RAMP2 and -3 on the activation and conformation of the CLR subunit of AM receptors, we mutated 68 individual amino acids in the juxtamembrane region of CLR, a key region for activation of AM receptors, and determined the effects on cAMP signaling. Sixteen CLR mutations had differential effects between the AM1 and AM2 receptors. Accompanying this, independent molecular modeling of the full-length AM-bound AM1 and AM2 receptors predicted differences in the binding pocket and differences in the electrostatic potential of the two AM receptors. Druggability analysis indicated unique features that could be used to develop selective small molecule ligands for each receptor. The interaction of RAMP2 or RAMP3 with CLR induces conformational variation in the juxtamembrane region, yielding distinct binding pockets, probably via an allosteric mechanism. These subtype-specific differences have implications for the design of therapeutics aimed at specific AM receptors and for understanding the mechanisms by which accessory proteins affect G protein-coupled receptor function.

Keywords: G protein-coupled receptor (GPCR); GPCR; RAMP; adrenomedullin; allosteric regulation; cardiovascular disease; conformational change; extracellular loops; molecular modeling; receptor activity-modifying protein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenomedullin / genetics
  • Adrenomedullin / metabolism*
  • Amino Acid Sequence
  • Calcitonin Receptor-Like Protein / chemistry
  • Calcitonin Receptor-Like Protein / genetics
  • Calcitonin Receptor-Like Protein / metabolism*
  • Crystallography, X-Ray
  • Humans
  • Models, Molecular
  • Protein Binding
  • Receptor Activity-Modifying Protein 2 / chemistry
  • Receptor Activity-Modifying Protein 2 / genetics
  • Receptor Activity-Modifying Protein 2 / metabolism*
  • Receptor Activity-Modifying Protein 3 / chemistry
  • Receptor Activity-Modifying Protein 3 / genetics
  • Receptor Activity-Modifying Protein 3 / metabolism*
  • Receptors, Adrenomedullin / chemistry
  • Receptors, Adrenomedullin / genetics
  • Receptors, Adrenomedullin / metabolism
  • Sequence Alignment


  • CALCRL protein, human
  • Calcitonin Receptor-Like Protein
  • RAMP2 protein, human
  • RAMP3 protein, human
  • Receptor Activity-Modifying Protein 2
  • Receptor Activity-Modifying Protein 3
  • Receptors, Adrenomedullin
  • Adrenomedullin

Associated data

  • PDB/2L7S
  • PDB/3C59
  • PDB/4L6R
  • PDB/4RWF