Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase, which belongs to the silent information regulator 2 (Sir2) family of sirtuin histone deacetylases (HDACs). The yeast Sir2 protein and its mammalian derivatives play a central role in epigenetic gene silencing, DNA repair and recombination, cell-cycle, microtubule organization, and in the regulation of aging. We have isolated and characterized the human Sirt1 genomic sequence, which spans a region of 33,660 bp and which has one single genomic locus. Determination of the exon-intron splice junctions established that SIRT1 is encoded by 9 exons ranging in size from 80 bp (exon 6) to 2,120 bp (exon 9). Characterization of the 5' flanking genomic region, which precedes the Sirt1 open reading frame, revealed a CCAAT-box and a number of NF-κB and GATA transcription factor binding sites in addition to a small 350 bp CpG island. The 4,107 bp human Sirt1 mRNA has an open reading frame of 2,244 bp and encodes a 747 aa protein with a predictive molecular weight of 81.7 kDa and an isoelectric point of 4.55. Fluorescence in situ hybridization analysis localized the human Sirt1 gene to chromosome 10q21.3.

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