title: The composition and properties of the Escherichia coli 5-S RNA-protein complex.
abstract: At a high concentration of MgCl2 (30 mM) and a low concentration of proteins from the 50-S subunit (0.2 mg/ml), only three proteins, L15, L18 and L25, bind to 5-S RNA in significant amounts. On the other hand, in a buffer containing only 1 mM Mg Cl2, but otherwise at the same ionic strength (0.2 M), or at a protein concentration about 1.5 mg/ml, a large, stable complex can form between immobilized 5-S RNA and 50-S ribosomal proteins. This complex contains proteins L2, L3, L5, L15, L16, L17, L18, L21, L22, L25, L33 and L34, and it possess properties relevant to the function of the 50-S subunit; it has a binding site for deacylated tRNA, with a dissociation constant of 4.5 x 10(-7) M. The complex formed with 5-S RNA immobilized on an affinity column interacts also with 30-S subunits. The 5-S RNA-protein complex is interpreted as a sub-ribosomal domain which includes a considerable fraction of the peptidyl transferase center of the Escherichia coli ribosome.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D002846:Chromatography, Affinity; D004926:Escherichia coli / Q000378:metabolism*; D011485:Protein Binding; D012329:RNA, Bacterial / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D012343:RNA, Transfer