OPAL SUPPRESSOR TRNA GENES IN HUMAN AND OTHER GENOMES

在Higher中描述的唯一自然产生的无义抑制因子tRNA 真核生物是脊椎动物中存在的两种蛋白石抑制因子丝氨酸tRNA。 纸巾。这些tRNA有几个独特的特征：(1)它们是90 核苷酸的长度，因此是迄今为止测得最长的tRNA；(2) 它们在丝氨酸部分被磷酸化，形成磷酸丝氨酰-tRNA； (3)与其他tRNA相比，它们的修饰碱基较少；(4)它们是 由单个基因编码，即使发生了几个嘧啶转变 转录后，其中一个转换发生在反密码子中； (5)与任何其他已知的tRNA不同，初级转录本的出现没有 基因产物5‘端的加工；以及(6)基因进化 比其他tRNA基因更新。对近似值的检验 蛋白石磷酸丝氨酸基因在自然界中的起源和分布 基因只出现在动物王国，而不是在代表中 莫内拉、原生生物、真菌和植物界。在动物中，基因 出现在氯虫门的成员(被囊类、文昌鱼、七鳃鳗、 哈格鱼、角鲨、冬季比目鱼、非洲爪哇、鸡肉和牛)，但 不在节肢动物门、软体动物门、Aschelminths或 波里费拉。编码蛋白石抑制因子tRNAs的基因已经被 从人、兔、鸡和非洲爪哇基因组中分离和测序 非洲爪哇卵母细胞体内转录和HeLa体外转录 细胞提取液。非洲爪哇加工过的文字记录的指纹 基因表明基因被忠实地转录，并启动了 转录发生在基因内的第一个核苷酸。

The only naturally occurring nonsense suppressor tRNAs described in higher eukaryotes are two opal suppressor serine tRNAs that occur in vertebrate tissues. These tRNAs have several unique features: (1) they are 90 nucleotides in length and thus are the longest tRNAs sequenced to date; (2) they are phosphorylated on their serine moiety to form phosphoseryl-tRNA; (3) they have few modified bases compared to other tRNAs; (4) they are encoded by a single gene even though several pyrimidine transitions occur post-transcriptionally and one of the transitions occurs in the anticodon; (5) the primary transcript arises, unlike any other known tRNAs, without processing on the 5' side of the gene product; and (6) the gene evolved more recently than other tRNA genes. An examination of the approximate origin and distribution of the opal phosphoserine gene in nature has shown that the gene occurs only on the Animal Kingdom and not in representatives of the Monera, Protist, Fungi and Plant Kingdoms. Among animals the gene occurs in members of the Phylum Chlordata (tunicate, amphioxus, lamprey, hag fish, horned shark, winter flounder, Xenopus, chicken and bovine), but not in members within the Phyla Arthropoda, Mollusca, Aschelminthes or Porifera. The genes encoding the opal suppressor tRNAs which have been isolated and sequenced from human, rabbit, chicken and Xenopus genomes are transcribed in vivo in Xenopus oocytes and are transcribed in vitro in HeLa cell extracts. Fingerprints of the processed transcript from the Xenopus gene show that the gene is faithfully transcribed and that initiation of transcription occurs at the first nucleotide within the gene.