从哺乳期和怀孕豚鼠乳腺中分离出的核糖体的蛋白质合成活性。

The protein-synthesizing activity of ribosomes isolated from the mammary gland of lactating and pregnant guinea pigs.

作者信息

Fairhurst E, McIlreavy D, Campbell P N

出版信息

Biochem J. 1971 Aug;123(5):865-74. doi: 10.1042/bj1230865.

DOI:10.1042/bj1230865

PMID:5124390

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1177087/

Abstract

Polyribosome preparations were made from the deoxycholate-treated post-nuclear fractions obtained by the disruption of mammary glands from lactating and pregnant guinea pigs. 2. A high proportion of large polyribosomes was obtained from the glands of lactating animals whereas mainly small polyribosomes were obtained from the glands of pregnant animals. The isolated preparations incorporated [(14)C]phenylalanine into protein. The polyribosomes from the glands of pregnant animals were less active than those from the glands of lactating animals but the activity of the former was stimulated more by poly(U) than was the latter. 3. The ribosomes from mammary gland could be dissociated into subunits after incubation, under conditions necessary for protein synthesis, in the presence of puromycin. The subunits could be recombined to give a preparation that actively polymerized [(14)C]phenylalanine in the presence of poly(U). The subunits from guinea-pig mammary gland could be combined with subunits from liver of either guinea pig or rat. Hybrid ribosomes were also formed from subunits derived from glands of pregnant and lactating animals. The hybrids were as active as were the ribosomes formed by reassociation of subunits from the same tissue, suggesting that in this respect the ribosomes from pregnant animals were not defective. 4. Polyribosomes from mammary glands of lactating animals when incubated with cell sap from the same source were tested for their ability to synthesize alpha-lactalbumin. The polyribosomes were incubated in the presence of [(3)H]leucine and alpha-lactalbumin was isolated from the supernatant. The protein was finally treated with cyanogen bromide and the C-terminal and N-terminal fragments were separated and their radioactivity was determined. Both fragments were radioactive consistent with the synthesis of alpha-lactalbumin. 5. The results are discussed in relation to protein synthesis in the mammary gland after parturition.

摘要

多核糖体制剂是由经脱氧胆酸盐处理的核后组分制备而成，这些核后组分来自泌乳期和怀孕期豚鼠乳腺组织匀浆。2. 从泌乳期动物的腺体中获得了高比例的大多核糖体，而从怀孕期动物的腺体中主要获得的是小多核糖体。分离得到的制剂能将[¹⁴C]苯丙氨酸掺入蛋白质中。来自怀孕期动物腺体的多核糖体活性低于来自泌乳期动物腺体的多核糖体，但前者比后者对聚尿苷酸（poly(U)）的刺激反应更强烈。3. 在蛋白质合成所需的条件下，乳腺核糖体在嘌呤霉素存在的情况下孵育后可解离成亚基。这些亚基可以重新组合，形成一种在聚尿苷酸存在下能使[¹⁴C]苯丙氨酸积极聚合的制剂。豚鼠乳腺的亚基可以与豚鼠或大鼠肝脏的亚基结合。来自怀孕期和泌乳期动物腺体的亚基也能形成杂交核糖体。这些杂交核糖体与由同一组织的亚基重新结合形成的核糖体活性相同，这表明在这方面，怀孕期动物的核糖体并无缺陷。4. 将泌乳期动物乳腺的多核糖体与来自同一来源的细胞液一起孵育，检测其合成α-乳白蛋白的能力。多核糖体在[³H]亮氨酸存在的情况下孵育，然后从上层清液中分离出α-乳白蛋白。该蛋白质最终用溴化氰处理，分离出C末端和N末端片段并测定其放射性。两个片段均具有放射性，这与α-乳白蛋白的合成情况相符。5. 结合分娩后乳腺中的蛋白质合成情况对这些结果进行了讨论。