Soprano D R, Pickett C B, Smith J E, Goodman D S
J Biol Chem. 1981 Aug 25;256(16):8256-8.
A study was performed to identify the first translated product of messenger RNA for retinol-binding protein (RBP), the specific plasma transport protein for vitamin A. Poly(A)+RNA was isolated from rat liver and translated in the rabbit reticulocyte in vitro protein-synthesizing system. RBP was identified and separated from other translated products by immunoprecipitation with specific rabbit anti-rat RBP antiserum. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of the immunoprecipitate consistently revealed one major product which migrated more slowly than purified rat serum RBP. The protein (preRBP) had an approximate molecular weight of 24,000. When dog pancreas microsomal membranes were cotranslationally present, the newly synthesized preRBP was processed to a protein which migrated coincidentally with purified rat serum RBP, approximately 20,500 daltons. These results indicate that RBP is initially synthesized as a larger molecular weight precursor (preRBP) which is rapidly processed by the removal of a peptide of approximately 3,500 daltons to the size of the final RBP molecule that circulates in the plasma.
开展了一项研究，以鉴定视黄醇结合蛋白（RBP，维生素A的特异性血浆转运蛋白）信使核糖核酸的首个翻译产物。从大鼠肝脏中分离出聚腺苷酸加尾RNA（Poly(A)+RNA），并在兔网织红细胞体外蛋白质合成系统中进行翻译。通过用特异性兔抗大鼠RBP抗血清进行免疫沉淀，将RBP与其他翻译产物进行鉴定和分离。免疫沉淀物的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和荧光自显影始终显示出一种主要产物，其迁移速度比纯化的大鼠血清RBP慢。该蛋白（前体RBP）的分子量约为24,000。当共翻译存在狗胰腺微粒体膜时，新合成的前体RBP被加工成一种与纯化的大鼠血清RBP迁移一致的蛋白，约为20,500道尔顿。这些结果表明，RBP最初作为分子量更大的前体（前体RBP）合成，该前体通过去除约3,500道尔顿的肽而迅速加工成在血浆中循环的最终RBP分子大小。
