1. Dissociation Characteristics of Endothelin Receptor Agonists and Antagonists in Cloned Human Type-B Endothelin Receptor
- Author
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Terry J. Opgenorth, Jinshyun R. Wu-Wong, W. J. Chiou, S. Sundy, S R Magnuson, and Douglas B. Dixon
- Subjects
Endothelin Receptor Antagonists ,Endothelin receptor type A ,Physiology ,Recombinant Fusion Proteins ,CHO Cells ,Beta-1 adrenergic receptor ,Cricetinae ,Enzyme-linked receptor ,Animals ,Humans ,Receptor ,Glucagon-like peptide 1 receptor ,Protease-activated receptor 2 ,Sulfonamides ,Receptors, Endothelin ,Chemistry ,Endothelins ,Cell Biology ,General Medicine ,Receptor, Endothelin B ,Molecular biology ,Endothelin 1 ,Peptide Fragments ,Molecular Weight ,Kinetics ,Pyrimidines ,Endothelin receptor ,Oligopeptides ,Protein Binding - Abstract
The human type-B endothelin receptor (h-ETB) was cloned from human lung poly A+RNA and stably expressed in CHO cells. Endothelin (ET) receptor binding and stimulation of PI hydrolysis demonstrated that the cloned h-ETB receptor is functional and linked to intracellular signal transduction pathways in CHO cells. The molecular mass of the h-ETB receptor was determined to be 65 KDa, and Bmax and Kd were 0.36 pmol/mg and 80 pM, respectively. Competition studies employing receptor ligands revealed that the potencies of the test ligands (IRL1620, PD142893, and Ro46-2005) were dependent on the length of the incubation time, whereas the natural agonists (ET-1 and ET-3) were not. When competing with ET-1 in the h-ETB receptor binding, the IC50 increased from 1.2 nM to 8.2 nM for IRL1620, 0.068 microM to 1.9 microM for PD142893, and 0.76 microM to 12.7 microM for Ro46-2005, as the incubation time increased from 1 hr to 24 hr. These time-induced changes are likely due to differences in the dissociation characteristics between the artificial ligands and the natural ligands.
- Published
- 1997