Abstract
K'A (apparent association constant) and Bmax. (total receptor concentration) describing the interaction of tri-iodothyronine (T3) and its solubilized rat liver nuclear receptor (R) are found to be moderately consistent in successive preparations, but both quantities diminished after a few days. To achieve comparability in the effects of ionic strength (I) and of pH on K'A and Bmax, appropriate measurements have been made simultaneously on single preparations. K'A and Bmax. were found to be effectively unchanged over the range I0.05-0.60. Both parameters have been measured over the range pH 6.4-9.0 and the values of K'A analysed in terms of the 4'-OH ionization of T3 and that of a cationic acidic group, shown to require pK' = 7.6. This group could be identified either with the terminal alpha-NH3+ of T3 or with a group (RH+) in the receptor site. On the balance of evidence the first possibility is the more likely, in which case the variation of Bmax. with pH is ascribed to conformational changes in the receptor protein.
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Selected References
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- Apriletti J. W., Eberhardt N. L., Latham K. R., Baxter J. D. Affinity chromatography of thyroid hormone receptors. Biospecific elution from support matrices, characterization of the partially purified receptor. J Biol Chem. 1981 Dec 10;256(23):12094–12101. [PubMed] [Google Scholar]
- Benson M. G., Ellis D., Emmett J. C., Leeson P. D., Pearce N. J., Shah V. P., Underwood A. H. 3'-Acetyl-3,5-diiodo-L-thyronine: a novel highly active thyromimetic with low receptor affinity. Biochem Pharmacol. 1984 Oct 15;33(20):3143–3149. doi: 10.1016/0006-2952(84)90070-4. [DOI] [PubMed] [Google Scholar]
- Bolger M. B., Jorgensen E. C. Molecular interactions between thyroid hormone analogs and the rat liver nuclear receptor. Partitioning of equilibrium binding free energy changes into substituent group interactions. J Biol Chem. 1980 Nov 10;255(21):10271–10278. [PubMed] [Google Scholar]
- Eberhardt N. L., Ring J. C., Latham K. R., Baxter J. D. Thyroid hormone receptors. Alteration of hormone-binding specificity. J Biol Chem. 1979 Sep 10;254(17):8534–8539. [PubMed] [Google Scholar]
- GEMMILL C. L. The apparent ionization constants of the phenolic hydroxyl groups of thyroxine and related compounds. Arch Biochem Biophys. 1955 Feb;54(2):359–367. doi: 10.1016/0003-9861(55)90048-5. [DOI] [PubMed] [Google Scholar]
- Klotz I. M. Numbers of receptor sites from Scatchard graphs: facts and fantasies. Science. 1982 Sep 24;217(4566):1247–1249. doi: 10.1126/science.6287580. [DOI] [PubMed] [Google Scholar]
- LARDY H. Effect of thyroid hormones on enzyme systems. Brookhaven Symp Biol. 1955 Feb;7:90-7; discussion, 97-101. [PubMed] [Google Scholar]
- Latham K. R., Ring J. C., Baxter J. D. Solubilized nuclear "receptors" for thyroid hormones. Physical characteristics and binding properties, evidence for multiple forms. J Biol Chem. 1976 Dec 10;251(23):7388–7397. [PubMed] [Google Scholar]
- Wilson B. D., Wium C. A., Gent W. L. The binding of thyroid hormone receptors to DNA. Biochem Biophys Res Commun. 1984 Oct 15;124(1):29–36. doi: 10.1016/0006-291x(84)90911-2. [DOI] [PubMed] [Google Scholar]
- Wilson E. A. Extensive gangrene of the bowel after haemorrhagic shock: a case report. S Afr Med J. 1980 Mar 8;57(10):377–378. [PubMed] [Google Scholar]