A human testis-specific mRNA for phosphoribosylpyrophosphate synthetase that initiates from a non-AUG codon

Masanori Taira, Taizo Iizasa, Hideaki Shimada, Jun Kudoh, Nobuyoshi Shimizu, Masamiti Tatibana

研究成果: Article査読

62 被引用数 (Scopus)


Two highly homologous subunits for phosphoribosylpyrophosphate synthetase are encoded by human X-linked genes, PRPS1 and PEPS2 (Taira, M., Kudoh, J., Minoshima, S., Iizasa, T., Shimada, H., Shimizu, Y., Tatibana, M., and Shimizu, N. (1989b) Somat. Cell Mol. Genet. 15, 29-37). These genes are expressed in most tissues, whereas an additional unique mRNA (1.4 kilobases) is present in the testes of rats as well as mice and humans (Taira, M., Iizasa, T., Yamada, K., Shimada, H., and Tatibana, M. (1989a) Biochim. Biophys. Acta 1007, 203-208). In this paper, cDNA cloning revealed that the human testis-specific mRNA was encoded by an autosomal gene, termed PRPS3. RNA blot analysis showed that the expression of this gene began at 4 weeks of age in rats, coinciding with the reported appearance of primary spermatocytes. A cDNA clone of PRPS3 was sequenced and found to encode a predicted product of 317 amino acids which was highly homologous to those of PRPS1 and PRPS2 (94.3% and 91.2% identities, respectively). However, the PRPS3 cDNAs lacked an ATG initiator for translation at the expected position, and instead contained an ACG triplet. In vitro transcription/translation studies, combined with in vitro site-directed mutagenesis experiments, suggested that the ACG codon at this position did serve as a start codon. Analysis of amino-terminal sequence of the radiolabeled PRPS3 product, prepared by in vitro translation, supported the predicted sequence starting with Pro-1, and, in addition, this product was labeled with N-formyl[35S]methionyl-tRNAi. These results suggested that the synthesis of the nascent polypeptide could initiate with methionine at the position corresponding to the ACG codon.

ジャーナルJournal of Biological Chemistry
出版ステータスPublished - 1990 9月 25

ASJC Scopus subject areas

  • 生化学
  • 分子生物学
  • 細胞生物学


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