Sequence of membrane-associated thyroid hormone binding protein from bovine liver: its identity with protein disulphide isomerase.
The complementary DNAs of the bovine liver membrane-associated 3,5,3'-triiodo-L-thyronine binding protein with 55 k-dalton (T3BP) were cloned and the nucleotide sequences were determined. Monospecific antibodies against T3BP were used to screen a bovine liver cDNA library in lambda gtll. We analyzed the sequences of two cloned T3BP cDNAs. The clones encoded a polypeptide of 510 amino acid residues, including a signal peptide of 20 amino acid. Northern blot analysis of bovine and human RNA showed that the mRNAs encoding T3BP are 2.7 kilobase in length. Amino acid sequence of N-terminal and other three peptides isolated from purified T3BP were found in the predicted amino acid sequence from the cDNA sequence. The predicted amino acid sequence is closely homologous (93%) with that of rat protein disulphide isomerase (EC 5.3.4.1), which catalyzes the isomerization of the protein disulphide bonds and has been shown to play an important role in post-translational regulation. The results suggest that T3BP and protein disulphide isomerase should be the same protein.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis*; D007535:Isomerases / Q000235:genetics*; D008099:Liver / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases; D011988:Receptors, Thyroid Hormone / Q000235:genetics* / Q000302:isolation & purification; D013974:Thyroxine / Q000378:metabolism
D011988:Receptors, Thyroid Hormone; D004247:DNA; D007535:Isomerases; D019704:Protein Disulfide-Isomerases; D013974:Thyroxine