Expression of the c-myc gene, which produces an oncogenic transcription factor, is tightly regulated in normal cells but is frequently deregulated in human cancers. The protein encoded by this gene is a transcriptional repressor thought to negatively regulate MYC function, and is therefore a potential tumor suppressor. This protein inhibits the transcriptional activity of MYC by competing for MAX, another basic helix-loop-helix protein that binds to MYC and is required for its function. Defects in this gene are frequently found in patients with prostate tumors. Three alternatively spliced transcripts encoding different isoforms have been described. Additional alternatively spliced transcripts may exist but the products of these transcripts have not been verified experimentally. [provided by RefSeq, Jul 2008]
Function:
Transcriptional repressor. MXI1 binds with MAX to form a sequence-specific DNA-binding protein complex which recognizes the core sequence 5'-CAC[GA]TG-3'. MXI1 thus antagonizes MYC transcriptional activity by competing for MAX.
Subcellular Location:
Nucleus.
Tissue Specificity:
High levels found in the brain, heart and lung while lower levels are seen in the liver, kidney and skeletal muscle.
DISEASE:
Defects in MXI1 may be a cause of susceptibility to prostate cancer (PC) [MIM:171367]. It is a malignancy originating in tissues of the prostate. Most prostate cancers are adenocarcinomas that develop in the acini of the prostatic ducts. Other rare histopathologic types of prostate cancer that occur in approximately 5% of patients include small cell carcinoma, mucinous carcinoma, prostatic ductal carcinoma, transitional cell carcinoma, squamous cell carcinoma, basal cell carcinoma, adenoid cystic carcinoma (basaloid), signet-ring cell carcinoma and neuroendocrine carcinoma.
Similarity:
Contains 1 basic helix-loop-helix (bHLH) domain.
SWISS:
P50539
Gene ID:
921
Database links:
Entrez Gene: 921 Human
Entrez Gene: 17859 Mouse
Entrez Gene: 25701 Rat
Omim: 600020 Human
SwissProt: P50539 Human
SwissProt: P50540 Mouse
SwissProt: O09015 Rat
Unigene: 501023 Human
Unigene: 602078 Human
Unigene: 676603 Human
Unigene: 2154 Mouse
Unigene: 37510 Rat
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