Measurement of the millisecond activation switch of G protein-coupled receptors in living cells

Nat Biotechnol. 2003 Jul;21(7):807-12. doi: 10.1038/nbt838. Epub 2003 Jun 15.


Hormones and neurotransmitters transduce signals through G protein-coupled receptors (GPCR). Despite their common signaling pathways, however, the responses they elicit have different temporal patterns. To reveal the molecular basis for these differences we have developed a generally applicable fluorescence-based technique for real-time monitoring of the activation switch of GPCRs in living cells. We used such direct measurements to investigate the activation of the alpha(2A)-adrenergic receptor (alpha(2A)AR; neurotransmitter) and the parathyroid hormone receptor (PTHR; hormone) and observed much faster kinetics than expected: approximately 40 ms for the alpha(2A)AR and approximately 1 s for the PTHR. The different switch times are in agreement with the different receptors' biological functions. Agonists and antagonists could rapidly switch the receptors on or off, whereas a partial agonist caused only a partial signal. This approach allows the comparison of agonist and partial agonist intrinsic activities at the receptor level and provides evidence for millisecond activation times of GPCRs.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-2 Receptor Agonists
  • Adrenergic alpha-2 Receptor Antagonists
  • Cell Culture Techniques / methods*
  • Cell Line
  • Clonidine / pharmacology
  • GTP-Binding Proteins / chemistry*
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Kidney / chemistry
  • Kidney / drug effects
  • Kidney / metabolism
  • Parathyroid Hormone / pharmacology
  • Protein Binding
  • Receptor, Parathyroid Hormone, Type 1 / agonists
  • Receptor, Parathyroid Hormone, Type 1 / antagonists & inhibitors
  • Receptor, Parathyroid Hormone, Type 1 / chemistry
  • Receptors, Adrenergic, alpha-2 / metabolism
  • Receptors, G-Protein-Coupled / agonists
  • Receptors, G-Protein-Coupled / antagonists & inhibitors
  • Receptors, G-Protein-Coupled / chemistry*
  • Receptors, G-Protein-Coupled / metabolism*
  • Signal Transduction / physiology*
  • Spectrometry, Fluorescence / methods*


  • ADRA2A protein, human
  • Adrenergic alpha-2 Receptor Agonists
  • Adrenergic alpha-2 Receptor Antagonists
  • Parathyroid Hormone
  • Receptor, Parathyroid Hormone, Type 1
  • Receptors, Adrenergic, alpha-2
  • Receptors, G-Protein-Coupled
  • GTP-Binding Proteins
  • Clonidine