Isolation of a cDNA clone encoding a KATP channel-like protein expressed in insulin-secreting cells, localization of the human gene to chromosome band 21q22.1, and linkage studies with NIDDM.

Tsaur ML, Menzel S, Lai FP, Espinosa R, Concannon P, Spielman RS, Hanis CL, Cox NJ, Le Beau MM, German MS
Diabetes. 1995 44 (5): 592-6

PMID: 7729621 · DOI:10.2337/diab.44.5.592

The metabolism of glucose in insulin-secreting cells leads to closure of ATP-sensitive K+ channels (KATP), an event that initiates the insulin secretory process. Defects in insulin secretion are a common feature of non-insulin-dependent diabetes mellitus (NIDDM), and the beta-cell KATP that couples metabolism and membrane potential is a candidate for contributing to the development of this clinically and genetically heterogeneous disorder. We screened a hamster insulinoma cDNA library by low-stringency hybridization with a probe coding for the G-protein-coupled inwardly rectifying K+ channel GIRK1/KGA and isolated clones encoding a protein, KATP-2, whose sequence is 90% similar to that of the recently described KATP-1, an ATP-sensitive K+ channel expressed in heart and other tissues. RNA blotting showed that KATP mRNA was present in insulin-secreting cells and brain but not in heart. To assess the contribution of KATP-2 to the development of NIDDM, the human KATP-2 gene (symbol KCNJ7) was isolated and mapped to chromosome band 21q22.1 by fluorescence in situ hybridization. A simple tandem repeat DNA polymorphism, D21S1255, was identified in the region of the KATP-2 gene, and linkage studies between this marker and NIDDM were carried out in a group of Mexican-American sib pairs with NIDDM. There was no evidence for linkage between D21S1255 and NIDDM, indicating that KATP-2 is not a major susceptibility gene in this population.

MeSH Terms (22)

Adenosine Triphosphate Amino Acid Sequence Animals Base Sequence Chromosome Mapping Chromosomes, Artificial, Yeast Chromosomes, Human, Pair 21 Cricetinae Diabetes Mellitus, Type 2 DNA, Complementary DNA Primers Genetic Linkage Humans In Situ Hybridization, Fluorescence Insulin Insulin Secretion Islets of Langerhans Molecular Sequence Data Potassium Channels RNA, Messenger Tissue Distribution Tumor Cells, Cultured

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