HETEROGENEITY BETWEEN BRAIN AND PITUITARY CORTICOTROPIN-RELEASING FACTOR RECEPTORS IS DUE TO DIFFERENTIAL GLYCOSYLATION
HETEROGENEITY BETWEEN BRAIN AND PITUITARY CORTICOTROPIN-RELEASING FACTOR RECEPTORS IS DUE TO DIFFERENTIAL GLYCOSYLATION
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DOI：
10.1210/endo-125-4-1877
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发表时间：
1989-10-01
期刊：
影响因子：
4.8
通讯作者：
DESOUZA, EB
中科院分区：
文献类型：
--
作者：
GRIGORIADIS, DE;DESOUZA, EB
化学亲和交联研究已经鉴定出具有相似药理学特征但分子量不同的脑和垂体CRF受体（垂体前叶，75，000;脑，58，000）。为了确定CRF受体的异质性是否是蛋白质中固有的，我们使用凝集素亲和色谱法和外切和内切糖苷酶处理研究了两种类型CRF受体的糖蛋白性质。CRF受体在大脑皮层和垂体前叶吸附，并专门从刀豆球蛋白-A-和麦胚凝集素固定凝集素亲和柱洗脱，表明这两种形式的受体是含有复杂的和高甘露糖碳水化合物部分的糖蛋白。大脑皮质CRF受体对神经氨酸酶和α-肾上腺素敏感。甘露糖苷酶处理的脑垂体CRF受体，而脑垂体CRF受体只受到神经氨酸苷酶处理的影响，这表明脑和脑垂体中的CRF受体在其糖基化单位的性质上略有不同。用内切糖苷酶、N-聚糖酶处理大脑皮质或垂体前叶CRF受体后，mol wts显著降低;垂体前叶CRF受体的mol wt从75，000降低至约40，000 - 45，000，而相应地，皮质受体从58，000降低至约40，000 - 45，000。使用蛋白酶金黄色葡萄球菌V8（S. aureus V8）或木瓜蛋白酶，从垂体前叶或大脑皮质标记的CRF受体蛋白产生几乎相同的肽片段。总之，这些数据支持这样的假设，即脑和垂体中CRF受体的配体结合亚单位位于40，000 - 45，000的多肽上，并且在两种组织中似乎是相同的。发现在两种蛋白质的流动性中观察到的差异是由于两种组织中蛋白质的翻译后修饰的差异。
Chemical affinity cross-linking studies have identified brain and pituitary CRF receptors with similar pharmacological characteristics but different mol wts (anterior pituitary, 75,000; brain, 58,000). In order to determine whether the heterogeneous nature of CRF receptors was inherent in the protein, we examined the glycoprotein nature of both types of CRF receptors using lectin affinity chromatography and treatments with exo- and endoglycosidases. CRF receptors in both the cerebral cortex and anterior pituitary adsorbed to and specifically eluted from Concanavalin-A- and wheat germ agglutinin-immobilized lectin affinity columns, indicating that both forms of the receptor are glycoproteins containing complex and high-mannose carbohydrate moieties. Cerebral cortical CRF receptors were sensitive to both neuraminidase and .alpha.-mannosidase treatment while pituitary CRF receptors were only affected by neuraminadase treatment, suggesting that CRF receptors in brain and pituitary differed slightly in the nature of their glycosylation units. After treatment of cerebral cortical or anterior pituitary CRF receptors with the endoglycosidase, N-glycanase, the mol wts were markedly decreased; the mol wt of the anterior pituitary CRF receptor was decreased from 75,000 to approximately 40,000-45,000 while in a corresponding manner, the cortical receptor was decreased from 58,000 to approximately 40,000-45,000. Limited proteolysis after deglycosylation with N-glycanase using the proteinases Staphylococcus aureus V8 (S. aureus V8) or papain, generated virtually identical peptide fragments from anterior pituitary- or verebral cortex-labeled CRF receptor proteins. In summary, these data support the hypothesis that the ligand binding subunit of the CRF receptor in both brain and pituitary resides on a polypeptide of 40,000-45,000 and appears to be identical in both tissues. Differences observed in the mobility of the two proteins were found to be due to differences in the posttranslational modification of the proteins in the two tissues.