Diabetes Branch and National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20205.
Proc Natl Acad Sci U S A. 1982 Mar;79(6):2086-90. doi: 10.1073/pnas.79.6.2086.
Multiple molecular forms of immunoreactive corticotropin (ACTH) and beta-endorphin were present in extracts of a unicellular eukaryote (Tetrahymena pyriformis). One form of immunoreactive ACTH reacted similarly with two different ACTH antisera (one specific for the 11-24 sequence and the other with determinants within sequences 1-14 and 17-39) and migrated with synthetic hACTH-(1-39) in a gel filtration system. This form also exhibited ACTH bioactivity in a dispersed rat adrenal cell bioassay system, with a mean immunoassay/bioassay ratio of 1.5. Gel filtration revealed multiple size classes of immunoreactive beta-endorphin; a major peak of radioreceptor activity was detected which exhibited a K(av) similar to that of authentic beta-endorphin. A major portion of immunoreactive beta-endorphin-sized material exhibited retention times similar to those of synthetic human and camel beta-endorphin upon reverse-phase high-pressure liquid chromatography. These distinctive properties and specificities would seem to exclude the presence of limited homologies with sequences present in other proteins. High molecular weight material containing both ACTH and beta-endorphin antigenic determinants was also demonstrated, suggesting, but not proving, the presence of a common precursor molecule.
从一种单细胞真核生物（梨形四膜虫）的提取物中存在多种有免疫活性的促肾上腺皮质激素 (ACTH) 和β-内啡肽的分子形式。一种有免疫活性的 ACTH 与两种不同的 ACTH 抗血清反应相似（一种针对 11-24 序列，另一种针对 1-14 序列和 17-39 序列内的决定簇），并在凝胶过滤系统中与合成的 hACTH-(1-39) 一起迁移。这种形式在分散的大鼠肾上腺细胞生物测定系统中也表现出 ACTH 生物活性，免疫测定/生物测定比值的平均值为 1.5。凝胶过滤显示有多种大小类别的有免疫活性的β-内啡肽；检测到一个主要的放射受体活性峰，其 K(av) 与β-内啡肽相似。有相当一部分有免疫活性的β-内啡肽大小的物质在反相高效液相色谱中表现出与合成的人源和骆驼源β-内啡肽相似的保留时间。这些独特的性质和特异性似乎排除了与其他蛋白质中存在的有限同源性的可能性。还证明了含有 ACTH 和β-内啡肽抗原决定簇的高分子量物质的存在，这表明（但不能证明）存在共同的前体分子。
