Cloning and sequence analysis of TFE, a helix-loop-helix transcription factor able to recognize the thyroglobulin gene promoter in vitro.
A cDNA that encodes a transcription factor able to recognize the thyroglobulin gene promoter in vitro was isolated from a dog thyroid cDNA expression library in lambda gt11. The library was screened with a multimerized 20 bp-oligonucleotide probe corresponding to the -126 to -107 bp region of the bovine thyroglobulin gene promoter. The specificity of DNA sequence recognition was demonstrated by DNA binding experiments realized with beta-galactosidase-fusion protein immobilized on nitrocellulose filters and various unlabelled multimerized competing DNA fragments. The encoded protein, TFE, appears to be the canine counterpart of a recently cloned human transcription factor, ITF-2, that binds to the mu E5 kappa E2 motif found in both immunoglobulin heavy and light chains genes enhancers and belongs to the basic-Helix-Loop-Helix family of transcription factors. When TFE protein was produced in a rabbit reticulocyte lysate, it displayed the same specificity of DNA sequence recognition as the beta-galactosidase fusion protein and immobilization of the translation product on nitrocellulose still appeared to be essential for detecting in vitro DNA binding activity. Functional data failed to assign a role for TFE in the control of thyroglobulin gene transcription in vitro, suggesting that the selection of TFE clone resulted from the fortuitous presence of a high affinity binding site in the probe used for screening the expression library.
Javaux
F
F
IRIBHN, Université Libre de Bruxelles, Belgium.
Donda
A
A
Vassart
G
G
Christophe
D
D
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004285:Dogs; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D013954:Thyroglobulin / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D014157:Transcription Factors; D004247:DNA; D013954:Thyroglobulin