Fleckner J, Rasmussen H H, Justesen J
Department of Molecular Biology, University of Aarhus, Denmark.
Proc Natl Acad Sci U S A. 1991 Dec 15;88(24):11520-4. doi: 10.1073/pnas.88.24.11520.
An interferon gamma (IFN-gamma)-inducible protein, gamma 2, was identified by two-dimensional gel electrophoresis of transformed human amnion (AMA) cell proteins. cDNA clones coding for this protein have been isolated and characterized as encoding a polypeptide with a predicted molecular weight of 53,165 and a pI of 6.16. Both values are in good agreement with those observed in two-dimensional gel electrophoresis. The gamma 2 protein is found to be highly induced by IFN-gamma, whereas no induction was seen after addition of IFN-alpha to AMA cells. A gamma 2-specific 2.7-kilobase mRNA was likewise seen to accumulate selectively in response to IFN-gamma in these cells. Comparison of the predicted amino acid sequence of gamma 2 to proteins in GenBank data bases revealed that gamma 2 is highly homologous to rabbit peptide chain release factor [Lee, C. C., Craigen, W. J., Muzny, D. M., Harlow, E. & Caskey, C. T. (1990) Proc. Natl. Acad. Sci. USA 87, 3508-3512] and bovine tryptophanyl-tRNA synthetase [M. Garret, V. Trezeguet, B. Pajot, J. C. Gandar, M. Merle, M. Guegiev, J. P. Benedetto, C. Sarger, J. Alteriot, J. La Bouessec, J. Labouesse, and J. Bonnet (1990), GenBank accession no. X52113]. Amino acid sequence similarities of 94% and 97%, respectively, are found, which in general would indicate that gamma 2 represents the human equivalent to either of these two mammalian genes. Based on these sequence similarities, the current data raise the possibility that tryptophanyl-tRNA charging and peptide chain release are carried out by the same enzyme. The gamma 2 protein is shown to possess tryptophan-dependent aminoacyl-tRNA synthetase activity and thus constitutes an enzymatic activity involved in the biological activity of IFN-gamma.
通过对转化的人羊膜（AMA）细胞蛋白质进行二维凝胶电泳，鉴定出一种干扰素γ（IFN-γ）诱导蛋白γ2。已分离出编码该蛋白的cDNA克隆，并鉴定其编码一种预测分子量为53165且pI为6.16的多肽。这两个值与二维凝胶电泳中观察到的值非常一致。发现γ2蛋白受到IFN-γ的高度诱导，而将IFN-α添加到AMA细胞后未观察到诱导现象。同样，在这些细胞中，一种γ2特异性的2.7千碱基mRNA也被发现会响应IFN-γ而选择性积累。将γ2的预测氨基酸序列与GenBank数据库中的蛋白质进行比较，发现γ2与兔肽链释放因子[Lee, C. C., Craigen, W. J., Muzny, D. M., Harlow, E. & Caskey, C. T. (1990) Proc. Natl. Acad. Sci. USA 87, 3508 - 3512]和牛色氨酰-tRNA合成酶[M. Garret, V. Trezeguet, B. Pajot, J. C. Gandar, M. Merle, M. Guegiev, J. P. Benedetto, C. Sarger, J. Alteriot, J. La Bouessec, J. Labouesse, and J. Bonnet (1990), GenBank accession no. X52113]高度同源。分别发现氨基酸序列相似性为94%和97%，这总体上表明γ2代表这两个哺乳动物基因中任何一个的人类等效物。基于这些序列相似性，目前的数据提出了色氨酰-tRNA负载和肽链释放可能由同一种酶进行的可能性。γ2蛋白显示具有色氨酸依赖性氨酰-tRNA合成酶活性，因此构成了参与IFN-γ生物活性的一种酶活性。
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