Khan M S, Maden B E
Eur J Biochem. 1978 Mar;84(1):241-50. doi: 10.1111/j.1432-1033.1978.tb12162.x.
18-S rRNA from HeLa cells was digested with nuclease S1. Under the conditions employed 15% of the total nucleotides and some 50% of the methylated nucleotides were released as low-molecular-weight products. The material which was precipitable by 70% ethanol after nuclease S1 digestion was subjected to further digestion by combined T1 plus pancreatic ribonucleases or by T1 ribonuclease alone, and fingerprints were prepared. It was found that the four sites which are modified late during ribosome maturation, and which contain base modifications, were all accessible to nuclease S1. By contrast fewer than one-half of the sites which are modified early during ribosome maturation, and which contain 2'-O-methyl groups, were accessible to nuclease S1; the remainder were protected, presumably by secondary or tertiary interactions within 18-S rRNA.
用核酸酶S1消化来自HeLa细胞的18 - S rRNA。在所采用的条件下，15%的总核苷酸和约50%的甲基化核苷酸以低分子量产物的形式释放出来。核酸酶S1消化后能用70%乙醇沉淀的物质，再用T1核糖核酸酶和胰核糖核酸酶联合消化或仅用T1核糖核酸酶进一步消化，并制备指纹图谱。结果发现，在核糖体成熟后期被修饰且含有碱基修饰的四个位点，对核酸酶S1均是可及的。相比之下，在核糖体成熟早期被修饰且含有2'-O-甲基基团的位点，只有不到一半对核酸酶S1是可及的；其余的受到保护，推测是由于18 - S rRNA内的二级或三级相互作用。
