Conformational changes of human beta 1 thyroid hormone receptor induced by binding of 3,3',5-triiodo-L-thyronine.
To understand the structural basis in the hormone-dependent transcriptional regulation of human beta 1 thyroid hormone receptor (h-TR beta 1), we studied the conformational changes of h-TR beta 1 induced by binding of 3,3',5-triiodo-L-thyronine (T3). h-TR beta 1 was treated with trypsin alone or in the presence of T3, thyroid hormone response element (TRE) or T3 together with TREs. Without T3, h-TR beta 1 was completely digested by trypsin. Binding of TREs had no effect on the tryptic digestion pattern. However, T3-bound h-TR beta 1 became resistant to tryptic digestion and yielded trypsin-resistant peptide fragments with molecular weight of 28,000 and 24,000. Chymotryptic digestion also yielded a T3-protected 24 Kd peptide fragment. Using anti-h-TR beta 1 antibodies and amino acid sequencing, the 28 Kd fragment was identified to be Ser202-Asp456. The 24 Kd tryptic fragments were found to be Lys239-Asp456 and Phe240-Asp456. The 24 Kd chymotryptic fragment was identified to be Lys235-Asp456. The structural changes as a result of T3 binding could serve as a transducing signal to modulate the gene regulating activity of h-TR beta 1.
Bhat
M K
MK
Laboratory of Molecular Biology, DCBDC, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Parkison
C
C
McPhie
P
P
Liang
C M
CM
Cheng
S Y
SY
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001345:Autoradiography; D001483:Base Sequence; D001666:Binding Sites, Antibody; D006801:Humans; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D014176:Protein Biosynthesis; D011487:Protein Conformation / Q000187:drug effects*; D017433:Protein Structure, Secondary / Q000187:drug effects*; D011988:Receptors, Thyroid Hormone / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D013462:Sulfur Radioisotopes; D014284:Triiodothyronine / Q000378:metabolism* / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D011988:Receptors, Thyroid Hormone; D011994:Recombinant Proteins; D013462:Sulfur Radioisotopes; D014284:Triiodothyronine; D008715:Methionine