Sussman D J, Lai E Y, Fulton C
J Biol Chem. 1984 Jun 10;259(11):7355-60.
Actin, the major protein of Naegleria gruberi, is selectively not synthesized during the differentiation of amebae to flagellates. When RNA extracted from cells at intervals during differentiation is translated in the wheat germ cell-free system, a major translation product with the electrophoretic mobility of actin is seen to disappear with time during differentiation. This translation product is shown to be actin by its electrophoretic mobility, copolymerization with rabbit actin, peptide map, and immunoprecipitation by antibodies specific to Naegleria actin. Multiple isoforms of actin are synthesized in the cell-free system. Quantitative immunoprecipitation of translation products was employed to measure the relative amount of actin mRNA. Translatable actin mRNA begins to decrease in abundance within 7 min after the initiation of differentiation and thereafter decreases with a half-life of about 25 min. The selective disappearance of this major translatable mRNA provides a favorable opportunity to dissect the rules governing the half-life of a specific mRNA.
肌动蛋白是格氏耐格里原虫的主要蛋白质，在变形虫向鞭毛虫分化过程中它被选择性地不合成。当在分化过程中每隔一段时间从细胞中提取的RNA在麦胚无细胞系统中进行翻译时，可见具有肌动蛋白电泳迁移率的主要翻译产物在分化过程中随时间消失。通过其电泳迁移率、与兔肌动蛋白的共聚、肽图谱以及耐格里原虫肌动蛋白特异性抗体的免疫沉淀，表明该翻译产物为肌动蛋白。在无细胞系统中合成了多种肌动蛋白同工型。采用翻译产物的定量免疫沉淀法来测量肌动蛋白mRNA的相对量。可翻译的肌动蛋白mRNA在分化开始后7分钟内丰度开始下降，此后以约25分钟的半衰期下降。这种主要可翻译mRNA的选择性消失为剖析控制特定mRNA半衰期的规则提供了一个有利的机会。
