The ATP-sensitive K-channel plays a central role in insulin release from pancreatic β-cells. We report here the cloning of the gene (KCNJ6) encoding a putative subunit of a human ATP-sensitive K-channel expressed in brain and β-cells, and characterisation of its exon-intron structure. Screening of a somatic cell mapping panel and fluorescent in situ hybridization place the gene on chromosome 21 (21q22.1–22.2). Analysis of single-stranded conformational polymorphisms revealed the presence of two silent polymorphisms (Pro-149: CC G -CC A and Asp328: GA C -GA T ) with similar frequencies in normal and non-insulin-dependent diabetic patients.