Characterization of precursor and secreted forms of rat angiotensinogen.
Characterization of precursor and secreted forms of rat angiotensinogen.
复制标题
大鼠血管紧张素原前体和分泌形式的表征。
DOI：
10.1210/endo-114-3-776
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发表时间：
1984
期刊：
影响因子：
4.8
通讯作者：
P. Corvol
中科院分区：
文献类型：
--
作者：
D. Campbell;J. Bouhnik;E. Coezy;F. Pinet;E. Clauser;J. Ménard;P. Corvol
使用免疫沉淀和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳将兔网织红细胞裂解物用大鼠肝RNA引发的血管紧张素原前体与大鼠肝癌细胞和大鼠肝细胞分泌的血管紧张素原进行比较。用衣霉素抑制糖基化可以鉴定分泌的血管紧张素原的非糖基化形式。而肝癌细胞和肝细胞分泌的血管紧张素原表现出电泳异质性（mol wt，52-62 X 10(3]），衣霉素处理的细胞仅分泌单一血管紧张素原种类[mol wt，48.3 +/- 0.7 X 10(3)（平均值+/- SD）]，可以被肾素裂解。两种假定的血管紧张素原前体在网织红细胞裂解物：52.5 +/- 1.0 X 10(3) mol wt 的主要蛋白和 55.7 +/- 1.3 X 10(3) mol wt 的次要蛋白。这些蛋白代表单独的血管紧张素原前体的证据包括： 1) 两种蛋白均被五种不同的多克隆抗体和两种单克隆抗体识别。 2) 两种蛋白在网织红细胞中平行增加。裂解物用肾切除大鼠的肝脏 RNA 进行处理，并给予增加肝脏血管紧张素原产生的激素。 3) 两种蛋白质均被肾素裂解，产生 47.6 +/- 0.8 X 10(3) mol wt 的单一蛋白质。 4)通过肾素处理裂解物产生的脱-血管紧张素I-血管紧张素原具有与通过肾素处理由衣霉素处理的肝癌细胞和肝细胞分泌的非糖基化血管紧张素原产生的脱-AI-血管紧张素原相同的电泳迁移率。这些研究表明，大鼠肝脏合成两种独立的血管紧张素原前体，它们可能仅在前原序列的大小上有所不同。分泌的血管紧张素原的异质性可以完全由该分子的天冬酰胺残基的N-糖基化差异来解释。血管紧张素原的糖基化对于其合成、加工和分泌或其被肾素的水解并不是必需的。
Angiotensinogen precursors synthesized by rabbit reticulocyte lysate primed with rat liver RNA were compared with angiotensinogen secreted by rat hepatoma cells and rat hepatocytes using immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Inhibition of glycosylation with tunicamycin permitted identification of the nonglycosylated form of secreted angiotensinogen. Whereas angiotensinogen secreted by hepatoma cells and hepatocytes showed electrophoretic heterogeneity (mol wt, 52-62 X 10(3], tunicamycin-treated cells secreted only a single angiotensinogen species [mol wt, 48.3 +/- 0.7 X 10(3) (mean +/- SD)], which could be cleaved by renin. Two putative angiotensinogen precursors were synthesized in the reticulocyte lysate: a major protein of 52.5 +/- 1.0 X 10(3) mol wt and a minor protein of 55.7 +/- 1.3 X 10(3) mol wt. Evidence that these proteins represent separate angiotensinogen precursors includes the following. 1) Both proteins were recognized by five different polyclonal antibodies and two monoclonal antibodies. 2) Both proteins increased in parallel in reticulocyte lysates primed with liver RNA from rats nephrectomized and given hormones that increase liver angiotensinogen production. 3) Both proteins were cleaved by renin to produce a single protein of 47.6 +/- 0.8 X 10(3) mol wt. 4) The des-angiotensin I-angiotensinogen generated by renin treatment of the lysate had an electrophoretic mobility identical to that of des-AI-angiotensinogen produced by renin treatment of nonglycosylated angiotensinogen secreted by tunicamycin-treated hepatoma cells and hepatocytes. These studies suggest that rat liver synthesizes two separate angiotensinogen precursors which may differ only in the size of their prepro sequence. The heterogeneity of secreted angiotensinogen can be fully accounted for by differences in N-glycosylation of asparagine residues of the molecule. Glycosylation of angiotensinogen is not essential for its synthesis, processing, and secretion or its hydrolysis by renin.