CHARACTERIZATION OF CORTICOTROPIN RECEPTORS ON ADRENOCORTICAL-CELLS
CHARACTERIZATION OF CORTICOTROPIN RECEPTORS ON ADRENOCORTICAL-CELLS
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DOI：
10.1073/pnas.78.12.7431
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发表时间：
1981-01-01
期刊：
影响因子：
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通讯作者：
RAMACHANDRAN, J
中科院分区：
文献类型：
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作者：
BUCKLEY, DI;RAMACHANDRAN, J
在[[125 I] ITyr 23，Phe 2，Nle 4]ACTH-（1-38）（125 I-ACTH类似物）的帮助下，研究了ACTH与分离的大鼠肾上腺皮质细胞上的受体的结合，所述[125 I] ITyr 23，Phe 2，Nle 4]ACTH-（1-38）（125 I-ACTH类似物）保留了完全的生物学效力，并且具有1800 ± 1的比放射性。75 Ci/mmol。结合是高度特异性的肾上腺皮质细胞，和放射性肽被置换低浓度的促肾上腺皮质激素，但不是由其他基本肽。结合是快速的、可逆的，并且与细胞数量呈线性相关。125 I-ACTH类似物在23 ℃与细胞孵育时没有显著降解。C下保温1h。结合的Scatchard分析与单一类别的结合位点相容，Kd = 1.41。0.21 nM，并且位点的数目估计为3840 . ±.每个牢房1045人结合曲线与cAMP的浓度-反应曲线重叠。少量但显著量的125 I-ACTH类似物在足以最大刺激类固醇生成的浓度下结合。对于一系列ACTH类似物，cAMP产生的半最大刺激所需的肽的浓度与结合的半最大抑制所需的浓度非常一致。肾上腺皮质细胞显然只含有一类ACTH受体，刺激这些受体的一小部分（< 3%）就足以产生最大的类固醇。
The binding of ACTH to receptors on isolated rat adrenocortical cells was investigated with the aid of [[125I]ITyr23, Phe2, Nle4]ACTH-(1-38) (125I-ACTH analog) which retained full biological potency and had a specific radioactivity of 1800 .+-. 75 Ci/mmol. Binding was highly specific to adrenocortical cells, and the radioactive peptide was displaced by low concentrations of ACTH but not by other basic peptides. Binding was rapid, reversible and linearly related to the number of cells. 125I-ACTH analog was not significantly degraded by incubation with the cells at 23.degree. C for 1 h. Scatchard analysis of the binding was compatible with a single class of binding sites with Kd = 1.41 .+-. 0.21 nM, and the number of sites was estimated to be 3840 .+-. 1045 per cell. The binding curve was superimposable on the concentration-response curve for cAMP. Small, but significant amounts of 125I-ACTH analog were bound at concentrations sufficient for maximal stimulation of steroidogenesis. For a series of ACTH analogs, the concentrations of the peptides required for half-maximal stimulation of cAMP production were in excellent agreement with the concentration required for half-maximal inhibition of binding. The adrenocortical cells apparently contain only 1 class of ACTH receptors and stimulation of a small fraction of these receptors (< 3%) may be sufficient for maximal steroidogenesis.