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Myc and Max proteins possess distinct transcriptional activities.

Kretzner, L and Blackwood, E M and Eisenman, R N (1992) Myc and Max proteins possess distinct transcriptional activities. Nature, 359 (6394). pp. 426-429. ISSN 0028-0836

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The Myc family proteins are thought to be involved in transcription because they have both a carboxy-terminal basic-helix-loop-helix-zipper (bHLH-Z) domain, common to a large class of transcription factors, and an amino-terminal fragment which, for c-Myc, has transactivating function when assayed in chimaeric constructs. In addition, c-, N- and L-Myc proteins heterodimerize, in vitro and in vivo, with the bHLH-Z protein Max. In vitro, Max homodimerizes but preferentially associates with Myc, which homodimerizes poorly. Furthermore Myc-Max heterodimers specifically bind the nucleotide sequence CACGTG with higher affinity than either homodimer alone. The identification of Max and the specific DNA-binding activities of Myc and Max provides an opportunity for directly testing the transcriptional activities of these proteins in mammalian cells. We report here that Myc overexpression activates, whereas Max overexpression represses, transcription of a reporter gene. Max-induced repression is relieved by overexpression of c-Myc. Repression requires the DNA-binding domain of Max, whereas relief of repression requires the dimerization and transcriptional activation activities of Myc. Both effects require Myc-Max-binding sites in the reporter gene.

Item Type: Article or Abstract
DOI: 10.1038/359426a0
PubMed ID: 1406956
Keywords or MeSH Headings: Animals; Base Sequence; Binding Sites/genetics; Chloramphenicol O-Acetyltransferase/biosynthesis; GTP-Binding Proteins; Gene Expression Regulation; Genes, Regulator/physiology; Molecular Sequence Data; Mutation; Promoter Regions (Genetics)/physiology; Proteins/physiology; Proto-Oncogene Proteins c-myc/physiology; Trans-Activation (Genetics)/physiology; Transcription, Genetic/physiology; Transfection;
Subjects: Molecules > Molecular structure
Molecules > Proteins
Molecules > Genes > Oncogenes
Cellular and Organismal Processes > Genetic processes > Transcription
Depositing User: Library Staff
Date Deposited: 02 Dec 2008 18:21
Last Modified: 07 May 2010 20:24

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