Yip C C, Hew C L, Hsu H
Proc Natl Acad Sci U S A. 1975 Dec;72(12):4777-9. doi: 10.1073/pnas.72.12.4777.
RNA preparations from isolated rat pancreatic islets and from human insulinomas were injected into oocytes of Xenopus laevis which were then incubated with [3H]leucine. Acid-ethanol extracts of the oocytes were immunoprecipitated with anti-insulin serum using the double antibody technique. Sodium dodecyl sulfate disc gel electrophoresis of the immunoprecipitates showed the presence of an insulin-displaceable immunoreactive material with a molecular weight of about 18,000 in extracts from oocytes injected with RNA of 9-11 S. This immunoreactive product was not detected in extracts from oocytes injected with buffer or 4-8S RNA or RNA heavier than 11 S. These observations suggest the involvement of a precursor larger than proinsulin in the biosynthesis of insulin.
将从分离的大鼠胰岛和人胰岛素瘤中提取的RNA制剂注射到非洲爪蟾的卵母细胞中，然后将这些卵母细胞与[3H]亮氨酸一起孵育。采用双抗体技术，用抗胰岛素血清对卵母细胞的酸乙醇提取物进行免疫沉淀。对免疫沉淀物进行十二烷基硫酸钠圆盘凝胶电泳，结果显示，在注射了9 - 11S RNA的卵母细胞提取物中，存在一种分子量约为18,000的可被胰岛素置换的免疫反应性物质。在注射了缓冲液、4 - 8S RNA或大于11S的RNA的卵母细胞提取物中未检测到这种免疫反应性产物。这些观察结果表明，胰岛素生物合成过程中涉及一种比胰岛素原更大的前体。
