Ion channels

Abstract:

The ATP-sensitive K-channel plays a central role in insulin release from pancreatic beta-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 beta-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: CCG-CCA and Asp-328: GAC-GAT) with similar frequencies in normal and non-insulin-dependent diabetic patients.

Abstract:

An amphibian homologue of the human cystic fibrosis transmembrane conductance regulator (CFTR) gene has been isolated from Xenopus laevis by polymerase chain reaction (PCR) amplification. The 4455bp sequence encodes a predicted polypeptide of 1485 amino acids which has an overall homology at the amino acid level of 77% identity and 88% similarity with human CFTR. Comparison of these evolutionarily diverse CFTR sequences has structure-function implications. Investigation of the expression of the Xenopus gene during early stages of development (Stages 1-48), using RNAase protection assays and PCR analysis of total Xenopus RNA, shows CFTR mRNA to be present at the very earliest stages of development, including the oocyte and blastula stages, with increasing amounts during subsequent development. The identification of mRNA for a CFTR homologue in the Xenopus oocyte and early stages of development has implications for its biological role.