Kambe F, Seo H, Murata Y, Matsui N
Department of Endocrinology and Metabolism, Nagoya University, Japan.
Mol Endocrinol. 1988 Feb;2(2):181-5. doi: 10.1210/mend-2-2-181.
An adult human liver cDNA library constructed in expression vector, bacteriophage lambda gt11, was screened with polyclonal antibody directed against human T4-binding globulin (TBG). TBG cDNA cloned in the present study was 944 nucleotides in length. It contained approximately 70% of the coding region and complete 3'-untranslated region. When the sequence was compared with that of TBG cDNA recently cloned by I. L. Flint, T. J. Bailey, T. A., Gustafson, B. E. Markham, and E. Morkin, the 3'-untranslated region of our cDNA was 231 nucleotides shorter than their cDNA. These results indicated that two TBG mRNAs with different length of 3'-untranslated regions may exist in human liver. Indeed, Northern blot analysis revealed that two TBG mRNAs differing in the length approximately 200 base pairs were present in normal human liver as well as in human hepatoma cell line (HepG2). It was demonstrated that this size difference was due to the length of 3'-untranslated region by hybridization with a probe specific to the longer 3'-end. Together with the sequence data, it was suggested that these two TBG mRNA species may be produced by alternative processing and polyadenylation at two different sites.
用针对人甲状腺素结合球蛋白（TBG）的多克隆抗体筛选构建于表达载体λ噬菌体gt11中的成人肝脏cDNA文库。本研究中克隆的TBG cDNA长度为944个核苷酸。它包含大约70%的编码区和完整的3'非翻译区。当将该序列与I. L. Flint、T. J. Bailey、T. A. Gustafson、B. E. Markham和E. Morkin最近克隆的TBG cDNA序列进行比较时，我们的cDNA的3'非翻译区比他们的cDNA短231个核苷酸。这些结果表明，人肝脏中可能存在两种3'非翻译区长度不同的TBG mRNA。事实上，Northern印迹分析显示，正常人肝脏以及人肝癌细胞系（HepG2）中存在两种长度相差约200个碱基对的TBG mRNA。通过与较长3'端特异性探针杂交证明，这种大小差异是由于3'非翻译区的长度所致。结合序列数据表明，这两种TBG mRNA可能是由两个不同位点的可变加工和多聚腺苷酸化产生的。
