Steps involved in the processing of common precursor forms of adrenocorticotropin and endorphin in cultures of mouse pituitary cells.
Steps involved in the processing of common precursor forms of adrenocorticotropin and endorphin in cultures of mouse pituitary cells.
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涉及小鼠垂体细胞培养物中促肾上腺皮质激素和内啡肽的常见前体形式的加工的步骤。
DOI：
10.1021/bi00610a030
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发表时间：
1978
期刊：
影响因子：
2.9
通讯作者：
Edward Herbert
中科院分区：
文献类型：
--
作者：
J. Roberts;M. Phillips;Patricia A. Rosa;Edward Herbert
研究了小鼠垂体瘤细胞（AtT-20）中促肾上腺皮质激素（ACTH）和内啡肽共同前体加工的初始步骤。用十二烷基硫酸钠（NaDodSO_4）-聚丙烯酰胺凝胶电泳分离出三种形式的前体，其表观分子量分别为29000（29 KACTH-内啡肽）、32000（32 KACTH-内啡肽）和34000（34 KACTH-内啡肽）。这些形式具有相似的肽骨架，但它们的碳水化合物含量不同。特别是，在32 K ACTH-内啡肽中观察到胰蛋白酶糖肽，它不存在于29 K ACTH-内啡肽中，并被鉴定为含有ACTH α（22- 39）序列的胰蛋白酶肽。在一些较小分子量形式的ACTH中观察到碳水化合物的类似异质性，其通过NaDodSO 4凝胶电泳解析。使用放射性氨基酸和糖的脉冲追踪和连续标记研究表明，29 K ACTH-内啡肽通过添加碳水化合物转化为32 K和34 K ACTH-内啡肽。糖肽和脉冲追踪研究表明，29 K ACTH-内啡肽在加工途径中处于分支点。它可以通过蛋白水解加工转化为4.5K ACTH，或者通过进一步添加碳水化合物转化为32 K ACTH-内啡肽。然后，32 K ACTH-内啡肽可以转化为13 K ACTH，4.5K ACTH的糖基化形式（Eipper，B.A.，& Mains，，R.E.（1977）J.Biol.Chem.252，882）。比较小鼠垂体提取物和小鼠垂体肿瘤细胞中不同分子量形式的ACTH和内啡肽的分布，揭示垂体含有肿瘤细胞中所见的所有形式的ACTH和内啡肽，包括ACTH-内啡肽前体的三种形式。然而，在小鼠垂体前叶和中叶中的形式的分子量分布是非常不同的。
The initial steps in the processing of the common precursor to adrenocorticotropin (ACTH) and endorphin in mouse pituitary tumor cells (AtT-20) have been investigated. Three forms of the precursor have been resolved by sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis with apparent molecular weights of 29 000 (29K ACTH-endorphin), 32 000 (32K ACTH-endorphin) and 34 000 (34K ACTH-endorphin). These forms have a similar peptide backbone, but their carbohydrate content differs. In particular, a tryptic glycopeptide has been observed in 32K ACTH-endorphin which is not present in 29K ACTH-endorphin and has been identified as the tryptic peptide containing the alpha(22--39) sequence of ACTH. Similar heterogeneity in carbohydrate has been observed in some of the smaller molecular weight forms of ACTH which are resolved by NaDodSO4 gel electrophoresis. Pulse chase and continuous labeling studies using radioactive amino acids and sugars suggest that the 29K ACTH-endorphin is converted to 32K and 34K ACTH-endorphin by the addition of carbohydrate. The glycopeptide and pulse chase studies suggest that 29K ACTH-endorphin is at a branch point in the processing pathways. It can either be converted to 4.5K ACTH by proteolytic processing or to 32K ACTH-endorphin by the further addition of carbohydrate. The 32K ACTH-endorphin can then be converted to 13K ACTH, the glycosylated form of 4.5K ACTH (Eipper, B.A., & Mains,, R.E. (1977) J.Biol. Chem.252, 882), by proteolytic processing. A comparison of the distribution of the different molecular weight forms of ACTH and endorphin in mouse pituitary extracts and in the mouse pituitary tumor cells reveals that the pituitary contains all of the forms of ACTH and endorphin seen in the tumor cells, including the three forms of the ACTH-endorphin precursor. However, the molecular weight distribution of the forms in the anterior lobe is very different from that in the intermediate lobe of mouse pituitary.