Subtilisin/kexin isozyme-1 (SKI-1), otherwise known as Site-1 protease (S1P), is a Golgi proteinase mediating the proteolytic activation of the precursor to sterol-regulated element-binding proteins (SREBPs) 1 and 2, two transcriptional factors that regulate expression of a variety of genes involved in cholesterol and lipid metabolism. Using PCR and RFLP analysis on a panel of genomic DNA from a mouse intersubspecific back-cross, we have mapped the SK1-/S1P gene (locus symbol: Mbtps1) to the distal part of mouse chromosome 8, in a region that exhibits synteny homology to the human chromosome 16q24 region where its orthologue had been previously mapped.