[Cloning of human thyroxine-binding globulin cDNA, isolation of the gene, and its transcriptional regulation].

Cloning of human thyroxine-binding globulin (TBG) cDNA and gene revealed that the primary structure of TBG and its gene organization are homologous to those of serine protease inhibitors (serpin). The transfection study of the TBG promoter linked to chloramphenicol acetyltransferase gene demonstrated that the putative hepatocyte nuclear factor-1 site (located at -77 approximately -65) is required for the transcription of the TBG gene. In addition, the sequence located at -218 approximately -102 is responsible for liver-specific expression of the gene. Estrogen, thyroid hormone and glucocorticoid had little effect on the promoter activity, suggesting that the alteration of serum TBG concentration by these hormones is due to their effect on posttranslational steps in TBG synthesis and secretion.