BINDING OF L-TRIIODOTHYRONINE TO ISOLATED RAT LIVER AND KIDNEY NUCLEI UNDER VARIOUS CIRCUMSTANCES

1976 ◽  
Vol 81 (1) ◽  
pp. 82-95 ◽  
Author(s):  
R. Docter ◽  
T. J. Visser ◽  
J. T. Stinis ◽  
N. L. van den Hout-Goemaat ◽  
G. Hennemann
Keyword(s):  
Rat Liver ◽  
Binding Sites ◽  
Association Constant ◽  
Binding Capacity ◽  
Binding Protein ◽  
Isolated Rat Liver ◽  
Relative Affinity ◽  
Liver And Kidney ◽  
Maximal Binding ◽  
Isolated Rat

ABSTRACT Triiodothyronine (T3) is specifically bound by nuclei from rat liver and kidney. Binding of T3 at 37°C reaches its maximum at 30 min. In the presence of EDTA (to remove Mg2+) T3 binds to a class of binding sites with an estimated equilibrium association constant (Ka) of 3.3 × 1010 m−1 and a maximal binding capacity (MBC) of 3.8 fmol T3/100 μg DNA. In the presence of MgCl2 T3 binds to a second class of binding sites with an estimated Ka of 4.8 × 108 m−1 and a MBC of 123 fmol/100 μg DNA. Among the analogues tested, binding - relative to T3 - of D-T3, triiodothyroacetic acid and desamino-T3 is the same for both classes of binding sites, but relative affinity of thyroxine, D-T4, tetraiodothyroacetic acid and desamino-T4 is 2.5 to 6 times higher for the second class of binding sites than for the first class. The presence of a cytosol binding protein is not a prerequisite for binding of T3 to the nucleus.

The uptake of R-type cobalamin-binding protein by isolated rat liver cells

1982 ◽  
Vol 720 (2) ◽  
pp. 203-210 ◽  
Author(s):  
J. Lindemans ◽  
E.J.M. de Jongh ◽  
F.C.M. Brand ◽  
M. Schoester ◽  
J. Van Kapel ◽  
...  
Keyword(s):  
Rat Liver ◽  
Binding Protein ◽  
Liver Cells ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Isolated Rat

Different alterations of nuclear triiodothyronine receptor capacity in liver and kidney induced by starvation and triiodothyronine administration

1985 ◽  
Vol 108 (2) ◽  
pp. 206-210 ◽  
Author(s):  
Hirotoshi Nakamura ◽  
Toshihiko Yokota ◽  
Hiroo Imura
Keyword(s):  
Body Weight ◽  
Nuclear Receptor ◽  
Rat Liver ◽  
Nuclear Protein ◽  
Binding Capacity ◽  
Association Constants ◽  
Liver And Kidney ◽  
Maximal Binding ◽  
Different Tissues

Abstract. Many studies have shown alterations in the number of nuclear triiodothyronine receptor (NT3R) under pathophysiologic situations. Most of these studies were performed on the rat liver and it is not known whether NT3R in different tissues exhibits an alteration similar to that in the liver. We compared the change of nuclear receptor capacity for T3 in the liver and kidney during starvation and after T3 injection. Fasting for 72 h decreased maximal binding capacity (Cmax) in the rat liver receptor to 67% of the control, while it did not significantly change Cmax in the kidney. These changes in Cmax were parallel to those of nuclear protein concentrations in both tissues. Daily sc injection of T3 (20 μg/100 g body weight) for 3 days also caused the different alteration of Cmax in the liver and kidney. After T3, hepatic NT3R increased to 182% of the control, but renal NT3R increased only to 136%. Association constants were the same in all groups. These results show that changes of NT3R capacity under some conditions vary in different tissues.

Formation and metabolism of a glutathione-S-conjugate in isolated rat liver and kidney cells

1978 ◽  
Vol 83 (1) ◽  
pp. 195-200 ◽  
Author(s):  
Peter Moldèus ◽  
Dean P. Jones ◽  
Kari Ormstad ◽  
Sten Orrenius
Keyword(s):  
Rat Liver ◽  
Kidney Cells ◽  
Isolated Rat Liver ◽  
Liver And Kidney ◽  
Isolated Rat

Existence of nuclear thyroid hormone receptors in the porcine thyroid gland and the rat thyroid cell line FRTL-5

1988 ◽  
Vol 117 (1) ◽  
pp. 116-124 ◽  
Author(s):  
Hirotoshi Nakamura ◽  
Hiroo Imura
Keyword(s):  
Rat Liver ◽  
Association Constant ◽  
Binding Capacity ◽  
Size Exclusion ◽  
Nuclear Proteins ◽  
Thyroid Cell ◽  
Scatchard Analysis ◽  
Thyroid Cells ◽  
Maximal Binding ◽  
Rat Thyroid

Abstract. We have investigated whether nuclear T3 receptors exist in the thyroid cell. Nuclear proteins extracted from porcine thyroid nuclei with 0.4 mol/l KCl were incubated with [125I]T3. The mixture was then analysed by sucrose density gradient ultracentrifugation which revealed that the T3-binding proteins migrated at the same position of 3.6 S as rat liver nuclear T3 receptors. Fractionation by high performance liquid chromatography using a size exclusion column and an ion exchanger column also demonstrated elution patterns of T3-binding similar to those of the rat liver receptor. Scatchard plots of crude nuclear extracts from porcine thyroid represented a curvilinear pattern. However, when the nuclear proteins partially purified by a DEAE column chromatography were analysed, a single binding component was found; the association constant was 4.1 × 1010 l/mol and the maximal binding capacity was 602 fmolT3/mg protein. Displacement study with several T3 analogues showed a highly selective affinity for L-T3. Cultured rat thyroid cells of the FRTL-5 line also contained a single class of saturable, high affinity T3-binding site. Subconfluent cells in 100-mm dishes were incubated with increasing amounts of [125I]T3 at 37°C for 3 h and radioactive T3 in isolated nuclei was counted. Scatchard analysis of data showed that the association constant and the maximal binding capacity were 3.44 ± 0.63 × 1010 1/mol and 63.7 ± 17.8 fmolT3/mg protein, respectively. These results strongly suggest that there are nuclear T3 receptors, indistinguishable from the hepatic T3 receptors, in the porcine thyroid and rat FRTL-5 cells.

Sign in / Sign up

Export Citation Format

Share Document