Abstract
1. 125I-Endothelin (ET)-1 binding to the rat anterior pituitary gland was saturable and single, with a K d of 71 pM and a B max of 120 fmol/mg.
2. When 1.0 μM BQ-123 (ETA antagonist) was added to the incubation buffer, the binding parameters were 8.3 pM and 8.0 fmol/mg, whereas 10 nM sarafotoxin S6c (ETBagonist) exerted little change in these binding parameters (K d,72pM;B max, 110 fmol/mg).
3. ETB receptor-related compounds such as sarafotoxin S6c, ET-3, IRL1620, and BQ-788 competitively inhibited 125I-ET-1 binding, only when 1.0 μM BQ-123 was present in the incubation buffer.
4. Thus, the ETB receptor is capable of binding ET-1 when the ETA receptor is being occupied by BQ-123. A collaboration mechanism between the ETA and the ETB receptor may function in the recognition of ET-1, a typical “bivalent” ligand.
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Himeno, A., Shigematsu, K., Taguchi, T. et al. Endothelin-1 Binding to Endothelin Receptors in the Rat Anterior Pituitary Gland: Interaction in the Recognition of Endothelin-1 Between ETA and ETB Receptors. Cell Mol Neurobiol 18, 447–452 (1998). https://doi.org/10.1023/A:1022557717481
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DOI: https://doi.org/10.1023/A:1022557717481