A functional site of the GTPase‐associated center within 28S ribosomal RNA probed with an anti‐RNA autoantibody.
A functional site of the GTPase‐associated center within 28S ribosomal RNA probed with an anti‐RNA autoantibody.
复制标题
用抗 RNA 自身抗体探测 28S 核糖体 RNA 内 GTP 酶相关中心的功能位点。
作者：
T. Uchiumi;R. Kominami
采用抗RNA自身抗体（anti - 28S）鉴定真核28S核糖体RNA中被称为“GTPase中心”的结构域的结构和功能元件特征。该抗体是核糖体相关GTP水解的抑制剂，具有独特的性质：它与真核生物的RNA结构域结合，而不与原核生物的RNA结构域结合。抗体结合发生在Mg2+存在下，保护了三个保守碱基（U1958， G1960和A1990）和原核生物23S rRNA中被A取代的碱基G1959（大肠杆菌中的A1067）免受化学修饰。G1959在体外被A取代后，抗体的结合能力明显减弱，而大肠杆菌结构域的A1067‐‐>G的相互取代则赋予了抗体的结合能力。这表明G碱基决定了抗体结合的特异性。G1959还受到核糖体与延伸因子EF‐2的关联的保护。结果表明，EFG对大肠杆菌碱A1067的保护作用[D]。Moazed, i.m.r oberson和H.F.Noller (1988) Nature, 334, 362 - 364]，认为G1959在真核生物中的位置和A1067在原核生物中的位置至少构成了因子结合位点的一部分，而与进化过程中的碱基替换无关。
An anti‐RNA autoantibody (anti‐28S) was employed to identify structural and functional elements characteristic of a domain termed the ‘GTPase center’ in eukaryotic 28S ribosomal RNA. This antibody, an inhibitor of ribosome‐associated GTP hydrolysis, has a unique property: it binds to the RNA domain of eukaryotes but not to that of prokaryotes. The antibody binding occurred in the presence of Mg2+ and protected from chemical modification three conserved bases (U1958, G1960 and A1990) and the base G1959 which is replaced by A in prokaryotic 23S rRNA (A1067 in Escherichia coli). In vitro substitution of G1959 to A drastically weakened the antibody binding, and the reciprocal substitution, A1067‐‐>G of the E.coli domain conferred the binding ability. This suggests that the G base determines the specificity of antibody binding. The G1959 was also protected by the association of ribosomes with elongation factor EF‐2. The result, together with protection of E.coli base A1067 by EFG [D.Moazed, I.M.Robertson and H.F.Noller (1988) Nature, 334, 362‐364], suggests that the position of G1959 in eukaryotes and A1067 in prokaryotes constitutes at least part of the factor binding site irrespective of the base replacement during evolution.