Nuclear proteins from the rat pituitary gland bind to regulatory sequences of the thyrotrophin-beta gene.
Interactions between DNA sequences and nuclear proteins are important in the regulation of gene expression. We have applied a gel retardation method to examine the binding of nuclear proteins from the rat pituitary gland to regulatory sequences of the rat TSH beta-subunit gene. Binding between nuclear protein and DNA is demonstrated by an alteration in electrophoretic mobility of the DNA. A 0.4 M NaCl fraction of pituitary nuclear proteins bound to a fragment of DNA containing the promoter region of the TSH-beta gene, but not to plasmid DNA or insulin cDNA of comparable size. This nuclear protein fraction also bound to fragments of DNA containing sequences from the 5'-flanking region of the gene; binding of nuclear proteins was evident as far as 1 kb 5' to the structural gene. Each of these regions of the TSH-beta gene formed a number of distinct complexes with the nuclear protein extract, distinguished by their differing binding affinities in the presence of poly(dI-dC), and by their electrophoretic mobility. These findings suggest that transcriptional regulation of the rat TSH-beta gene may be mediated by interaction of a number of nuclear proteins with regulatory sequences of DNA up to 1 kb upstream of the transcriptional start site of the gene.
Department of Medicine, University of Birmingham, Queen Elizabeth Hospital.
J A
JA
Ahlquist
J A
JA
Franklyn
D B
DB
Ramsden
M C
MC
Sheppard
D000818:Animals; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000032:analysis; D004247:DNA / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000032:analysis* / Q000166:cytology / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D012045:Regulatory Sequences, Nucleic Acid; D013972:Thyrotropin / Q000235:genetics / Q000378:metabolism*
D009687:Nuclear Proteins; D013972:Thyrotropin; D004247:DNA