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Negative cooperativity in the human bradykinin B2 receptor

A Pizard1, J Marchetti, J Allegrini

  • 1INSERM Unité 367, Physiologie et Pathologie Expérimentale Vasculaires, Paris, France.

The Journal of Biological Chemistry
|January 27, 1998
PubMed

Insights

Researchers studied the bradykinin (BK) B2 receptor, finding that BK binding exhibits negative cooperativity. This interaction accelerates ligand dissociation and decreases receptor affinity, potentially contributing to receptor desensitization.

Area of Science:

  • Pharmacology
  • Molecular Biology
  • Cell Biology

Background:

  • The bradykinin (BK) B2 receptor plays a crucial role in physiological processes.
  • Understanding BK B2 receptor kinetics is essential for drug development and therapeutic strategies.

Purpose of the Study:

  • To establish and characterize a high-density human kidney BK B2 receptor expression system in CHO-K1 cells.
  • To investigate the binding kinetics and molecular interactions of BK with its B2 receptor.

Main Methods:

  • Transfection of CHO-K1 cells with human kidney BK B2 receptor cDNA.
  • High-density receptor expression and characterization.
  • Kinetic analysis of BK-receptor binding and dissociation.
  • Guanine nucleotide effects on receptor binding.

Main Results:

  • A stable cell line expressing high-density BK B2 receptors (1.3 x 10(6) receptors/cell) was established.
  • BK binding kinetics did not fit a simple two-affinity state model.
  • Negative cooperativity was observed in BK-B2 receptor binding, evident in ligand dissociation rates.
  • This negative cooperativity was independent of guanine nucleotide presence.

Conclusions:

  • BK B2 receptor binding exhibits negative cooperativity, where receptor-receptor interactions accelerate ligand dissociation.
  • This phenomenon likely decreases the apparent affinity of the receptor for BK.
  • Negative cooperativity may play a significant role in the desensitization of BK B2 receptors.

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