Isolation of cDNAs for DNA-binding proteins which specifically bind to a tax-responsive enhancer element in the long terminal repeat of human T-cell leukemia virus type I.
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Tsujimoto A, Nyunoya H, Morita T, Sato T, Shimotohno K
Isolation of cDNAs for DNA-binding proteins which specifically bind to a tax-responsive enhancer element in the long terminal repeat of human T-cell leukemia virus type I.
J Virol. 1991 Mar;65(3):1420-6.
- PubMed ID
- 1847461 [ View in PubMed]
- Abstract
One of the gene products of human T-cell leukemia virus type I (HTLV-I), p40tax, activates its own viral transcription in trans through tax-responsive enhancers in viral long terminal repeats. Five species of cDNA clones for proteins that bind to the tax-responsive enhancer element in HTLV-I were isolated from the Jurkat cell library. The beta-galactosidase fusion protein prepared from the lysogen of a clone specifically recognized the cyclic AMP-responsive element in HTLV-I enhancer. The nucleotide sequence of a full-length cDNA clone (TAXREB67) had a coding capacity of 351 amino acids, which contained a basic motif followed by a leucine zipper structure near the carboxy terminus. Its mRNA was detected in human cell lines, including HTLV-I-infected or noninfected hematopoietic cell lines. The mRNA level in Jurkat cells was decreased temporarily by increasing cyclic AMP concentration but increased by increasing Ca2+ concentration. Polyclonal antibodies against the fusion protein specifically recognized a 52-kDa protein in Jurkat cells. Analyses of the function of this protein and its interactions with other cellular factors will be useful to help understand the regulatory mechanism through tax-responsive enhancers in HTLV-I.