[MYC_HUMAN] Note=Overexpression of MYC is implicated in the etiology of a variety of hematopoietic tumors. Note=A chromosomal aberration involving MYC may be a cause of a form of B-cell chronic lymphocytic leukemia. Translocation t(8;12)(q24;q22) with BTG1. Defects in MYC are a cause of Burkitt lymphoma (BL) [MIM:113970]. A form of undifferentiated malignant lymphoma commonly manifested as a large osteolytic lesion in the jaw or as an abdominal mass. Note=Chromosomal aberrations involving MYC are usually found in Burkitt lymphoma. Translocations t(8;14), t(8;22) or t(2;8) which juxtapose MYC to one of the heavy or light chain immunoglobulin gene loci.
[MAX_HUMAN] Transcription regulator. Forms a sequence-specific DNA-binding protein complex with MYC or MAD which recognizes the core sequence 5'-CAC[GA]TG-3'. The MYC-MAX complex is a transcriptional activator, whereas the MAD-MAX complex is a repressor. May repress transcription via the recruitment of a chromatin remodeling complex containing H3 'Lys-9' histone methyltransferase activity. [MYC_HUMAN] Participates in the regulation of gene transcription. Binds DNA in a non-specific manner, yet also specifically recognizes the core sequence 5'-CAC[GA]TG-3'. Seems to activate the transcription of growth-related genes.
X-ray structures of the basic/helix-loop-helix/leucine zipper (bHLHZ) domains of Myc-Max and Mad-Max heterodimers bound to their common DNA target (Enhancer or E box hexanucleotide, 5'-CACGTG-3') have been determined at 1.9 A and 2.0 A resolution, respectively. E box recognition by these two structurally similar transcription factor pairs determines whether a cell will divide and proliferate (Myc-Max) or differentiate and become quiescent (Mad-Max). Deregulation of Myc has been implicated in the development of many human cancers, including Burkitt's lymphoma, neuroblastomas, and small cell lung cancers. Both quasisymmetric heterodimers resemble the symmetric Max homodimer, albeit with marked structural differences in the coiled-coil leucine zipper regions that explain preferential homo- and heteromeric dimerization of these three evolutionarily related DNA-binding proteins. The Myc-Max heterodimer, but not its Mad-Max counterpart, dimerizes to form a bivalent heterotetramer, which explains how Myc can upregulate expression of genes with promoters bearing widely separated E boxes.
X-ray structures of Myc-Max and Mad-Max recognizing DNA. Molecular bases of regulation by proto-oncogenic transcription factors.,Nair SK, Burley SK Cell. 2003 Jan 24;112(2):193-205. PMID:12553908
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.