Intracellular polypeptide hormone receptors. The demonstration of specific binding sites for insulin and human growth hormone in Golgi fractions isolated from the liver of female rats.
Intracellular polypeptide hormone receptors. The demonstration of specific binding sites for insulin and human growth hormone in Golgi fractions isolated from the liver of female rats.
复制标题
细胞内多肽激素受体。
DOI：
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发表时间：
1978
影响因子：
4.8
通讯作者：
R. Sikstrom
中科院分区：
文献类型：
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作者：
J. Bergeron;B. Posner;Z. Josefsberg;R. Sikstrom
从雌性大鼠肝脏中分离的高尔基体和质膜片段显示了1251标记的胰岛素和1 ' 51标记的人生长激素（hGH）的特异性结合位点。高尔基体部分胰岛素结合水平低于质膜部分。相比之下，lz51-hGH的结合水平在高尔基体中比在质膜中高得多。还研究了光滑和粗糙微粒体的粗馏分以及纯化核。数据显示特异性结合微粒体部分，但没有显著结合的1z51-胰岛素或lz51-hGH纯化核。为了得出结论，在高尔基体部分中发现的结合位点不是由于等离子体外源碎片的污染，采用了一种与“特异性结合”实验相对应的形态学-逻辑技术。当新鲜制备的高尔基体与“i”标记的激素一起孵卵时，电镜放射自显影显示高尔基体囊泡膜上直接有高浓度的银颗粒（70%）。当这些分数与相同数量的标记激素孵育，但与额外的过量未标记的激素，颗粒的数量减少了90%，这表明放射自显影技术定位了特定的激素结合位点。比较了放射性标记激素与新鲜制备的高尔基体和冷冻解冻高尔基体的特异性结合。冻融后的片段特异性结合增强，形态被严重破坏。冻融质膜部分未发现激素结合增强。结果表明，激素结合位点定位于高尔基分泌囊泡的内或池面以及质膜的外或细胞外表面。
Golgi and plasmalemma fractions isolated from the livers of female rats showed specific binding sites for 1251-labeled insulin and 1”51-labeled human growth hormone (hGH). The level of insulin binding in the‘ Golgi fractions was lower than that in the plasmalemma fraction. In contrast, the level of lz51-hGH binding was much higher in the Golgi fractions than in the plasmalemma. Crude fractions of smooth and rough microsomes as well as purified nuclei were also studied. The data showed specific binding to the microsomal fractions, but no signifi- cant binding of either 1z51-insulin or lz51-hGH to purified nuclei. In order to conclude that the binding sites found in the Golgi fractions were not due to contamination by plasma- lemma fragments, a technique consisting of the morpho- logic counterpart to the “specific binding” assay was carried out. When freshly prepared Golgi fractions were incubated with ‘““I-labeled hormone, electron microscope radioautog- raphy revealed a high concentration of silver grains (70%) directly over the membranes of Golgi vesicles. When the fractions were incubated with the same amount of labeled hormone, but with an additional excess of unlabeled hor- mone, the number of grains was reduced by 90%, indicating that the radioautographic technique localized specific hor- mone binding sites. A comparison was made of the specific binding of the radiolabeled hormones to freshly prepared and frozen- thawed Golgi fractions. The frozen-thawed fractions showed augmented specific binding and morphologically were greatly disrupted. No enhancement of hormone binding was noted for the frozen-thawed plasmalemma fraction. The results suggest a localization of the hormone binding sites to the inner or cisternal face of the Golgi secretory vesicles and the outer or extracellular surface of the plasmalemma.