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Sequence-specific DNA binding by Myc proteins.
E Kerkhoff1, K Bister, K H Klempnauer
1Institute of Biochemistry, Medical School, University of Cologne, Federal Republic of Germany.
Summary
The carboxyl-terminal domain of Myc proteins is crucial for dimerization and DNA binding. A specific 61-amino acid region within this domain is sufficient for these essential functions.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Myc proteins possess a tripartite carboxyl-terminal domain with conserved motifs.
- These motifs are known to mediate protein-DNA and protein-protein interactions in transcription factors.
Purpose of the Study:
- To investigate the functional significance of sequence motifs in the Myc carboxyl-terminal domain.
- To determine the role of these motifs in Myc protein oligomerization and DNA binding.
Main Methods:
- Bacterial expression of recombinant avian v-Myc proteins with full-length or deleted alleles.
- Analysis of protein dimerization and specific DNA binding capabilities of recombinant v-Myc proteins.
Main Results:
- Recombinant v-Myc proteins retaining the carboxyl-terminal domain dimerize and bind DNA with the core sequence CACGTG.
- A 61-amino acid peptide containing the basic motif/helix-loop-helix domain is necessary and sufficient for dimerization and sequence-specific DNA binding.
Conclusions:
- The carboxyl-terminal domain is essential for v-Myc protein dimerization and DNA binding.
- The bipartite basic motif/helix-loop-helix domain is the minimal functional unit for these activities.