Metspalu E, Ustav M, Maimets T, Villems R
Eur J Biochem. 1982 Jan;121(2):383-9. doi: 10.1111/j.1432-1033.1982.tb05798.x.
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.
在高浓度氯化镁(30 mM)和低浓度50-S亚基蛋白(0.2 mg/ml)的条件下,只有三种蛋白,即L15、L18和L25能大量结合到5-S RNA上。另一方面,在仅含1 mM氯化镁但离子强度相同(0.2 M)的缓冲液中,或者在蛋白浓度约为1.5 mg/ml的情况下,固定化的5-S RNA与50-S核糖体蛋白之间能形成一个大的稳定复合物。该复合物包含蛋白L2、L3、L5、L15、L16、L17、L18、L21、L22、L25、L33和L34,并且具有与50-S亚基功能相关的特性;它有一个脱酰化tRNA的结合位点,解离常数为4.5×10⁻⁷ M。固定在亲和柱上的5-S RNA形成的复合物也与30-S亚基相互作用。5-S RNA-蛋白复合物被解释为一个亚核糖体结构域,它包含了大肠杆菌核糖体肽基转移酶中心的相当一部分。