Article Abstract:
The Myc oncoproteins comprise a family of DNA-binding proteins recognizing the sequence CACGTG and contain the basic helix-loop-helix and leucine zipper domains. Mutational analysis was conducted on various Myc analogs to identify critical residues in the basic region. The experiments identified a total of four amino acids which were involved in the formation of four consecutive turns of an alpha helix in the basic region. Two other conserved positions were not absolutely required for DNA binding.
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Article Abstract:
Gene expression in eukaryotic cells is regulated by proteins that initiate gene transcription. Among the most important eukaryotic gene regulatory proteins are repressors, which repress the expression of certain genes by binding DNA sites. Repression may be active, where the repressor acts on the basal transcription machinery to prevent an isomerization by stopping the addition of new proteins to the machinery irrespective of the number of activator genes in the cell.
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Article Abstract:
The homeodomain protein alpha-2 of Saccharomyces cerevisae binds weakly to target DNA sequences without the presence of a second DNA-binding protein, MCM1. The region within alpha-2, besides the homeodomain, responsible for target site selection was identified. The region was found adjacent to the homeodomain and could be transferred to other homeodomain proteins where it conferred the ability to interact with MCM1.
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