Characterization of specific binding sites for [3H]2-MeS-ADP on megakaryocytoblastic cell lines in culture

1994 ◽  
Vol 48 (1) ◽  
pp. 83-86 ◽  
Author(s):  
Pierre Savi ◽  
Armelle Troussard ◽  
Jean-Marc Herbert
Keyword(s):  
Cell Lines ◽  
Binding Sites ◽  
Specific Binding ◽  
Specific Binding Sites

scholarly journals Specific binding sites for synthetic growth hormone secretagogues in non-tumoral and neoplastic human thyroid tissue

2000 ◽  
Vol 165 (1) ◽  
pp. 139-146 ◽  
Author(s):  
P Cassoni ◽  
M Papotti ◽  
F Catapano ◽  
C Ghe ◽  
R Deghenghi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Cell Lines ◽  
Binding Sites ◽  
Specific Binding ◽  
Thyroid Tissue ◽  
Human Thyroid ◽  
Growth Hormone Secretagogues ◽  
Human Thyroid Tissue ◽  
Specific Binding Sites ◽  
Synthetic Growth

The presence of specific receptors for synthetic growth hormone secretagogues (GHSs) has been investigated in non-tumoral and neoplastic human thyroid tissue using a radio-iodinated peptidyl GHS ((125)I-labelled Tyr-Ala-hexarelin) as ligand. Specific binding sites for Tyr-Ala-hexarelin were detected in membranes from non-tumoral and follicular-derived neoplastic thyroid tissue, but not in thyroid tumours (medullary carcinomas) of parafollicular (C cell) origin. The binding activity was greatest in well differentiated neoplasms (papillary and follicular carcinomas), followed by poorly differentiated carcinomas, non-tumoral thyroid parenchyma, follicular adenomas and anaplastic carcinomas. Both peptidyl (Tyr-Ala-hexarelin, hexarelin, growth hormone releasing peptide (GHRP6) and non-peptidyl (MK 0677) GHSs completely displaced the radioligand from binding sites of non-tumoral thyroid gland, but MK 0677 was significantly less potent. The IC(50) values were (1. 9+/-0.3)x10(-8) mol/l for Tyr-Ala-hexarelin, (2.1+/-0.2)x10(-8) mol/l for hexarelin, (2.4+/- 0.3)x10(-8) mol/l for GHRP6 and only (1. 5+/-0.4)x 10(-7) mol/l for MK 0677. Similar IC(50) values were found in neoplastic thyroid tissue. Scatchard analysis of the binding revealed a finite number of binding sites in non-tumoral (B(max): 1232+/-32 fmol/mg protein, n=3) and neoplastic (papillary carcinomas) thyroid tissue (B(max): 2483+/-380 fmol/mg protein, n=5), with dissociation constants (K(d)) of (3.8+/-0.3)x10(-9) and (4. 4+/-0.6)x 10(-9) mol/l, respectively. On the basis of this evidence, we investigated the effects of some GHS on the proliferation of three different human follicular thyroid carcinoma cell lines (NPA, WRO and ARO) in which the presence of specific GHS receptors was also demonstrated. Tyr-Ala-hexarelin, GHRP6 and MK 0677 were able to inhibit serum-stimulated [(3)H]thymidine incorporation in NPA cells at concentrations close to their binding affinity. These substances also caused a significant inhibition of cell proliferation, which was evident at the earliest time of treatment (24 h) in all the cell lines, and at the latest time (96 h) in NPA cells only. In conclusion, this paper confirms the existence of specific binding sites for GHS in normal thyroid tissue and demonstrates, for the first time, that these binding sites are present in papillary and follicular carcinomas, low in anaplastic carcinomas and absent in medullary carcinomas of the thyroid. This work also provides evidence of a growth-inhibitory effect of GHS on cell lines derived from follicular thyroid cancers.

Characterization of specific binding sites for PAF in the iris and ciliary body of rabbit

1989 ◽  
Vol 160 (1) ◽  
pp. 250-256 ◽  
Author(s):  
M.T. Domingo ◽  
P.E. Chabrier ◽  
J.L. Van Delft ◽  
N.L. Verbeij ◽  
N.J. Van Haeringen ◽  
...  
Keyword(s):  
Binding Sites ◽  
Ciliary Body ◽  
Specific Binding ◽  
Specific Binding Sites

Characterization of Specific Binding Sites for Corticosterone in Mouse Liver Plasma Membrane

1989 ◽  
Vol 8 (4) ◽  
pp. 229-239 ◽  
Author(s):  
Miguel Trueba ◽  
IÑAki Ibarrola ◽  
Ana Isabel Vallejo ◽  
MarÍA José Sancho ◽  
Aida Marino ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Binding Sites ◽  
Mouse Liver ◽  
Specific Binding ◽  
Liver Plasma Membrane ◽  
Specific Binding Sites

scholarly journals Characterization of a thyroid-hormone-binding site on nuclear envelopes and nuclear matrices of the male-rat liver

1984 ◽  
Vol 219 (3) ◽  
pp. 1001-1007 ◽  
Author(s):  
Y A Lefebvre ◽  
J T Venkatraman
Keyword(s):  
Rat Liver ◽  
Binding Sites ◽  
Intact Animal ◽  
Binding Capacity ◽  
Specific Binding ◽  
Male Rat ◽  
Scatchard Analysis ◽  
Specific Binding Sites ◽  
Number Of Binding Sites

Nuclear envelopes and nuclear matrices were isolated from the male-rat liver. Incubation of 125I-labelled 3,3′,5-tri-iodothyronine (T3) with the nuclear-envelope fraction resulted in specific binding of T3 to the membranes. Maximum specific binding occurred at 30 degrees C after 2h incubation. Storage for 1 week at -80 degrees C resulted in no loss of binding. Scatchard analysis revealed a class of binding sites with KD 86 nM. 3,3′,5′-Tri-iodothyronine was as effective a competitor of [125I]T3 binding to nuclear envelopes as was L-T3 itself, and tri-iodothyroacetic acid was 70% as potent as T3. L- and D-thyronine did not compete for [125I]T3 binding. Incubation of nuclear envelopes with 0.6 M-NaCl before addition of T3 resulted in the complete loss of specific binding sites, whereas exposure of the membranes to 2.0 M-NaCl after incubation with T3 did not extract binding sites. Nuclear matrices, after incubation with [125I]T3 under the same conditions, were shown to possess a class of binding sites with a similar KD but with approx. 30% of the maximum binding capacity. Nuclear envelopes from hypothyroid animals may possess slightly lower numbers of binding sites compared with nuclear envelopes from the intact animal, whereas nuclear matrices from hypothyroid animals have the same number of binding sites as do nuclear envelopes from the intact animal. In conclusion, nuclear envelopes and nuclear matrices have a class of binding sites with relatively high affinity for T3. It is distinct from nuclear and cytosolic binding sites.

scholarly journals Solubilization and characterization of substance P-binding sites from chick brain membranes

1988 ◽  
Vol 252 (2) ◽  
pp. 545-551 ◽  
Author(s):  
H P Too ◽  
M R Hanley
Keyword(s):  
Substance P ◽  
Binding Sites ◽  
Specific Binding ◽  
Chick Brain ◽  
High Concentration ◽  
Brain Membrane ◽  
Brain Membranes ◽  
Specific Binding Sites ◽  
Octyl Glucoside

Sites binding monoiodinated-Bolton-Hunter-reagent-labelled substance P were solubilized from 1-day-old-chick brain membrane by using non-ionic detergents (1% digitonin/1% n-octyl glucoside) and a high concentration of NaCl (0.5 M). The solubilized preparation retained the pharmacological properties of the high-affinity binding sites found in the native membrane. The high density of specific binding sites (approximately 2 pmol of binding sites/mg of protein) suggests that the chick brain membranes may be a useful source for the purification of the substance P-binding sites.

Specific binding sites for epidermal growth factor and its effect on human chorionic gonadotrophin secretion by cultured tumour cell lines: comparison between trophoblastic and non-trophoblastic cells

1982 ◽  
Vol 101 (2) ◽  
pp. 281-286 ◽  
Author(s):  
Yukio Hirata ◽  
Satoru Sueoka ◽  
Masahito Uchihashi ◽  
Yoshio Yoshimoto ◽  
Takuo Fujita ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Lines ◽  
Binding Sites ◽  
Specific Binding ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Specific Binding Sites ◽  
Epidermal Growth ◽  
Tumour Cell Lines

Abstract. Using human trophoblastic (SCH) and non-trophoblastic (HeLa S3) tumour cell lines, specific binding sites for epidermal growth factor (EGF), a potent stimulator of growth in many tissues, and its effect on secretion of human chorionic gonadotrophin (hCG) and/ or its subunits were compared between these two tumour cells. Both SCH and HeLa S3 cells possessed two populations of specific binding sites for 125I-labelled EGF: the high affinity (Kd ∼10−10m) and the low affinity (Kd ∼ 7 × 10−10 m) system. Tetradecanoyl phorbol acetate (TPA), a tumour promotor, showed a potent competitor of labelled tracer binding to its receptor sites in both cell lines. EGF stimulated both hCG-α and hCG and/or hCG-β secretion in a dose-responsive manner from SCH cells, whereas it had no effect on hCG-α secretion from HeLa S3 cells. In contrast, dibutyryl cyclic AMP plus theophylline, a phosphodiesterase inhibitor, enhanced hCG-α secretion from both cells, while TPA had no effect in either cells. These data suggest that EGF may play a physiological role in hCG secretion from trophoblastic tissues and that the mechanism by which hCG and/or its subunits are secreted may differ between trophoblastic and non-trophoblastic tumour cells.

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