DNA binding by N- and L-Myc proteins.
N- and L-Myc, like c-Myc, contain adjacent basic region (BR), helix-loop-helix (HLH) and leucine zipper (LZ) motifs, which characterize a family of DNA-binding proteins. We have used a polymerase chain reaction (PCR)-based binding site selection technique to demonstrate that the most highly preferred binding site for both N- and L-Myc fusion proteins contains a CACGTG motif, the core binding sequence previously identified for c-Myc. Further analysis identified other N-Myc binding sequences, including asymmetric sequences such as CAT-GTG. N-Myc, like c-Myc, preferentially forms heterodimeric DNA-binding complexes with Max protein. Mutational analyses of N-Myc basic region (BR), helix-loop-helix (HLH) and leucine zipper (LZ) regions revealed that all three regions are necessary for DNA binding by N-Myc-Max complexes, and that dimerization requires both HLH and LZ motifs, while BR sequences are needed only for DNA binding. Our findings support the notion that the LZ motif is a critical element in dimer formation by bHLH-LZ proteins.
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Howard Hughes Medical Institute, Children's Hospital, Boston, Massachussetts 02115.
Moroy
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Collum
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Weintraub
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Alt
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Blackwell
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D016259:Genes, myc; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; C499329:Max protein, rat; C067850:Myc associated factor X; D010455:Peptides; D016271:Proto-Oncogene Proteins c-myc; D011994:Recombinant Proteins; D014157:Transcription Factors