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Nucleic Acids Res January 1, 2005; 33 (11): 3465-78.
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The 5''-AT-rich half-site of Maf recognition element: a functional target for bZIP transcription factor Maf.

Yoshida T , Ohkumo T , Ishibashi S , Yasuda K .

The Maf family of proteins are a subgroup of basic region-leucine zipper (bZIP) transcription factors, which recognize a long palindromic DNA sequence [TGCTGAC(G)TCAGCA] known as the Maf recognition element (MARE). Interestingly, the functional target enhancer sequences present in the alphaA-crystallin gene contain a well-conserved half-site of MARE rather than the entire palindromic sequence. To resolve how Maf proteins bind to target sequences containing only MARE half-sites, we examined their binding activities using electrophoretic gel mobility shift assays as well as in vitro and in vivo reporter assays. Our results indicate that the 5''-flanking region of the MARE half-site is required for Maf proteins to bind both in vitro and in vivo. The critical 5''-flanking sequences for c-Maf were determined by a selection and amplification binding assay and show a preference for AT-rich nucleotides. Furthermore, sequence analysis of the regulatory regions of several target genes also suggests that AT-rich sequences are important. We conclude that Maf can bind to at least two types of target sequences, the classical MARE (palindrome type) and a 5''-AT-rich MARE half-site (half-site type). Our results provide important new insights into the DNA binding and site selection by bZIP transcription factors.

PubMed ID: 15972792
PMC ID: PMC1156962
Article link: Nucleic Acids Res

Species referenced: Xenopus laevis
Genes referenced: actl6a hoxa3 hoxb3 il4 maf mafb mafg nrl pam thibz

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References [+] :
Angel, Phorbol ester-inducible genes contain a common cis element recognized by a TPA-modulated trans-acting factor. 1987, Pubmed