Dietrich A, Souciet G, Weil J H
J Biol Chem. 1987 Mar 25;262(9):4248-51.
Bean (Phaseolus vulgaris) chloroplastic and cytoplasmic leucyl-tRNA synthetases differ in their structural and catalytic properties and do not share common antigenic determinants. Polyadenylated mRNAs, prepared from young bean leaves, have been translated in vitro in a rabbit reticulocyte lysate cell-free system. The newly synthesized polypeptides have been submitted to immunoadsorption on protein A-Sepharose in the presence of the antibodies raised against the chloroplastic or the cytoplasmic leucyl-tRNA synthetase. The specificity of the immunoadsorption has been checked by competition experiments involving the pure enzymes. Bean chloroplastic leucyl-tRNA synthetase is synthesized in vitro from a polyadenylated mRNA as a precursor polypeptide of 130 kDa, which is somewhat larger than the mature enzyme of 120 kDa. Bean cytoplasmic leucyl-tRNA synthetase is synthesized in vitro as a polypeptide which has the size of the mature monomer (130 kDa). Processing of the precursor polypeptide of the chloroplastic leucyl-tRNA synthetase, yielding the mature enzyme, has been obtained by performing the in vitro translation in the presence of canine pancreatic microsomal membranes. These results suggest that in vivo bean chloroplastic leucyl-tRNA synthetase could be synthesized in the cytoplasm as a precursor which would be transported into the chloroplasts.
菜豆（Phaseolus vulgaris）的叶绿体和细胞质亮氨酰 - tRNA合成酶在结构和催化特性上存在差异，且不具有共同的抗原决定簇。从幼嫩菜豆叶片中制备的聚腺苷酸化mRNA已在兔网织红细胞裂解物无细胞体系中进行体外翻译。新合成的多肽在针对叶绿体或细胞质亮氨酰 - tRNA合成酶产生的抗体存在下，在蛋白A - 琼脂糖上进行免疫吸附。通过涉及纯酶的竞争实验检查了免疫吸附的特异性。菜豆叶绿体亮氨酰 - tRNA合成酶在体外由聚腺苷酸化mRNA合成，作为一种130 kDa的前体多肽，其比120 kDa的成熟酶略大。菜豆细胞质亮氨酰 - tRNA合成酶在体外作为具有成熟单体大小（130 kDa）的多肽合成。通过在犬胰腺微粒体膜存在下进行体外翻译，获得了叶绿体亮氨酰 - tRNA合成酶前体多肽加工产生成熟酶的过程。这些结果表明，在体内菜豆叶绿体亮氨酰 - tRNA合成酶可能在细胞质中作为前体合成，然后被转运到叶绿体中。
