Goodman H M, Olson M V, Hall B D
Proc Natl Acad Sci U S A. 1977 Dec;74(12):5453-7. doi: 10.1073/pnas.74.12.5453.
One of the eight endonuclease EcoRI fragments of yeast DNA that hybridize to yeast tRNATyr has been identified with the genetically defined nonsense-suppressor locus SUP4. This identification was achieved by analyzing the meiotic linkage between the genetic determinant for the SUP4 phenotype and that for an electrophoretic variant of the EcoRI fragment. The SUP4 gene was then cloned from an ochre-suppressing yeast strain and analyzed by DNA sequencing. A wild-type SUP4 gene and two other genetically unidentified tRNATyr genes were also sequenced. The sequence of the ochre suppressor differs from that of the wild-type genes by virtue of a G.C leads to T.A transversion in the base pair that codes for the wobble position base of the tRNATyr anticodon. All four genes contain, immediately to the 3' side of the anticodon triplet, a 14 base pair tract that is not present in mature tRNATyr. Although the four genes, which represent three unlinked chromosomal loci, all encode the same mature tRNA sequence, there is virtually no observable sequence homology between the three loci in the region preceding the 5' end of the mature tRNATyr sequences.
酵母DNA的八个能与酵母tRNATyr杂交的EcoRI片段之一，已被确定与遗传学上定义的无义抑制基因座SUP4相关。这种确定是通过分析SUP4表型的遗传决定因素与EcoRI片段电泳变体的遗传决定因素之间的减数分裂连锁来实现的。然后从一个赭石抑制型酵母菌株中克隆出SUP4基因，并进行DNA测序分析。还对一个野生型SUP4基因和另外两个遗传学上未鉴定的tRNATyr基因进行了测序。赭石抑制基因的序列与野生型基因的序列不同，原因是在编码tRNATyr反密码子摆动位置碱基的碱基对中发生了G.C到T.A的颠换。所有四个基因在反密码子三联体的3'侧紧邻处都含有一个14个碱基对的序列，该序列在成熟的tRNATyr中不存在。尽管这四个基因代表三个不连锁的染色体位点，都编码相同的成熟tRNA序列，但在成熟tRNATyr序列5'端之前的区域，这三个位点之间几乎没有可观察到的序列同源性。
