Johnson C H, Kruft V, Subramanian A R
Max-Planck-Institut für Molekulare Genetik, Abteilung Wittmann, Berlin, Federal Republic of Germany.
J Biol Chem. 1990 Aug 5;265(22):12790-5.
We describe the isolation and characterization of a chloroplast ribosomal protein and a clone of its cDNA. This protein has no homology to any Escherichia coli ribosomal protein or to any known proteins. Due to this novel finding we propose it be called PSrp-1, i.e. a plastid-specific ribosomal protein. The precursor form of PSrp-1, deduced from the cDNA sequence, is 302-amino acid residues long. The mature PSrp-1, identified by amino-terminal sequencing, is a protein of 236 residues. The NH2-terminal 66 amino acids form the transit peptide that targets PSrp-1 into the chloroplast. We show that PSrp-1 is a protein of the chloroplast 30 S ribosomal subunit by Western blotting and sequencing the excised protein after two-dimensional gel electrophoresis. The possible evolutionary origin of PSrp-1 from the nucleated host cell of the endosymbiont theory is discussed.
我们描述了一种叶绿体核糖体蛋白的分离和特性分析及其cDNA克隆。这种蛋白与任何大肠杆菌核糖体蛋白或任何已知蛋白均无同源性。基于这一新颖的发现，我们提议将其命名为PSrp - 1，即一种质体特异性核糖体蛋白。从cDNA序列推导得出的PSrp - 1前体形式长302个氨基酸残基。通过氨基末端测序鉴定的成熟PSrp - 1是一种由236个残基组成的蛋白质。氨基末端的66个氨基酸形成了将PSrp - 1靶向导入叶绿体的转运肽。我们通过蛋白质免疫印迹法以及对二维凝胶电泳后切下的蛋白质进行测序，证明PSrp - 1是叶绿体30 S核糖体亚基的一种蛋白质。文中还讨论了基于内共生理论，PSrp - 1可能从有核宿主细胞进化而来的起源。
