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Myc and Max associate in vivo.
E M Blackwood1, B Lüscher, R N Eisenman
1Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104.
Genes & Development
|January 1, 1992
Summary
Max and Myc proteins form a DNA-binding complex in vivo. Myc is rapidly degraded, suggesting its biosynthesis rate limits complex formation, highlighting Myc:Max interactions in gene regulation.
Area of Science:
- Molecular Biology
- Cell Biology
- Protein Interactions
Background:
- Max is a helix-loop-helix zipper protein that binds DNA with Myc family proteins.
- Myc and Max form sequence-specific DNA-binding complexes.
Purpose of the Study:
- To investigate the in vivo association of Myc and Max proteins.
- To characterize the stability and DNA-binding activity of the Myc:Max complex.
- To determine the factors regulating Myc:Max complex formation.
Main Methods:
- Coimmunoprecipitation assays using anti-Myc and anti-Max antibodies.
- Analysis of newly synthesized Myc protein.
- Assessment of DNA-binding activity of the Myc:Max complex.
- Investigation of Max protein localization, phosphorylation, and expression levels.
Main Results:
- Myc and Max proteins associate in vivo, forming a complex with specific DNA-binding activity for CACGTG sequences.
- Newly synthesized Myc is primarily found in complex with Max.
- Max is a stable nuclear protein, phosphorylated by casein kinase II, with stable expression levels across cell states.
- Myc is rapidly degraded during or after association with Max.
Conclusions:
- Myc:Max complex formation is regulated by Myc biosynthesis, which is likely the rate-limiting step.
- Max protein is stable and its expression is constant, while Myc protein levels are tightly controlled.
- Understanding Myc:Max interactions is crucial for comprehending gene regulation and cell cycle control.