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KMID : 0376219800170010091
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Chonnam Medical Journal
1980 Volume.17 No. 1 p.91 ~ p.98
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Thyroid Hormone Receptors : Binding of Triiodothyronine to Erythrocyte Membranes
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李民化/Lee, Min-wha
安鳳煥/李起榮/朴鐘一/Ahn, Bong-han/Lee, Kee-young/Park, Jong-il
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Abstract
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Specific triiodothyronine (T3)-binding activity was demonstrated in rabbit erythrocyte membranes.
The 1251-T3 binding was very rapid: half-maximal binding was obtained within 1 minute and maximal steady-state binding was reached after a 4-minute incubation at 22°C. Specific binding was sensitive to pH and showed an optimal pH at pH 7.4. Nonspecific binding, however, rose progressively at pHs below pH 7.4.
Scatchard analysis for the affinity and number of T3-binding sites in rabbit erythrocyte membranes demonstrated -the presence of two major classes of binding sites: those that have a high affinity-saturable binding sites (Ka=5.9x 109M-1) present in large number (apparent capacity of 2.9 pmol per ng of protein), and those that exhibit a much lower binding affinity but are difficult to saturate. Its specificity was such that T3 was bound at least 1,000 times more avidly than was L-thyroxine. 8-Anilino-l-naphthalene sulfonate at a micromolar concentration prevented the specific binding of T3 to erythrocyte membranes.
The presence of specific T3-binding sites in rabbit erythrocyte membranes suggests that thyroid hormones may be involved in the control of cell membrane functions.
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