CHROMOSOMAL LOCALIZATION AND CHARACTERIZATION OF THE STANNIN (SNN) GENE

Stannin is a protein that has been localized to trimethyltin-sensitive cell populations, and evidence suggests it plays a role in the toxic effects of organotins. In this study, we have isolated a mouse stannin genomic clone and have characterized the gene's intron-exon organizat ion, promoter region, and chromosomal location. We have also isolated a partial human stannin cDNA clone and analyzed the open reading frame . The mouse genomic clone spans similar to 19 kb and consists of one i ntron and two exons. The splice site consensus sequence was maintained at all intron-exon junctions. Promoter analysis suggests that two put ative promoter sites exist, each containing multiple regulatory elemen ts and transcription factor-binding sites. Fluorescence in situ hybrid ization analysis localized stannin to mouse Chromosome (Chr) 16 at ban d A2. This region is homologous to the proximal region of human Chr 16 (16p13) to which stannin has been previously mapped. Sequence analysi s revealed that the 264-bp open reading frame was identical between ra t and mouse. The human sequence was 98% identical, with two amino acid substitutions near the c-terminal end of the peptide. These data sugg est that stannin is highly conserved between species, and its unusual pattern of cellular expression may, in part, be explained via cell-spe cific promoters.