The sirtuins (SIRT1-7), also being referred to as class III HDACs, exert NAD-dependent deacetylase and/or ADP-ribosyltransferase activities in various cellular compartments including the cell nucleus, the cytoplasm and the mitochondria. The sirtuins play a central role in epigenetic gene silencing. DNA repair and recombination, cell-cycle, microtubule organization, and in the regulation of aging. SIRT4 is a mitochondrial protein that lacks deacetylase activities but efficiently works as an ADP-ribosyltransferase. We have isolated and characterized the murine Sirt4 genomic sequence, which spans a region of 12 kb and which has one single genomic locus. Determination of the exon-intron splice junctions established that SIRT4 is encoded by 6 exons. The 1648 bp murine Sirt4 transcript encodes a 418 aa protein with a predictive molecular weight of 47.3 kDa. Fluorescence in situ hybridization analysis identified a single genomic locus for murine Sirt4 gene on chromosome 5F and is neighbored by the PLA2G1B and PXN genes. (C) 2009 Elsevier Inc. All rights reserved.