Initial isolation and analysis of the human Kv1.7 (KCNA7) gene, a member of the voltage-gated potassium channel gene family Vladimir I. Kashuba a,b,c,1, * , Sergei M. Kvasha a,c,1 , Alexei I. Protopopov a,b,1 , Rinat Z. Gizatullin a , Alla V. Rynditch c , Claes Wahlestedt a , Wyeth W. Wasserman a , Eugene R. Zabarovsky a,b,d a Center for Genomics Research, Karolinska Institute, Stockholm, 171 77, Sweden b Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, 171 77, Sweden c Institute of Molecular Biology and Genetics, Ukrainian Academy of Sciences, Kiev, 252627, Ukraine d Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 117984, Russia Received 5 September 2000; received in revised form 19 February 2001; accepted 1 March 2001 Received by J.L. Slightom Abstract A novel human potassium channel gene was identi®ed and isolated. The maximal open reading frame encodes a protein of 456 amino acids. The predicted product exhibits 91% amino acid identity to the murine voltage-gated potassium channel protein Kv1.7 (Kcna7), which plays an important role in the repolarization of cell membranes. Based on the high similarity, the human gene has been classi®ed as the ortholog of the mouse Kcna7 and given the name Kv1.7 (KCNA7). A structural prediction identi®ed a pore region characteristic of potassium channels and six membrane-spanning domains. Northern expression analysis revealed the gene is expressed preferentially in skeletal muscle, heart and kidney. However, it is expressed at lower level in other tissues, including liver. A single mRNA isoform was observed, with a size of approximately 4.5 kb. Using ¯uorescence in situ hybridization, the gene was mapped to chromosomal band 19q13.4 (269.13 cR 3000 ). A genomic sequence was identi®ed in the database from this region, and the KCNA7 gene structure determined. Computational analysis of the genomic sequence reveals the location of a putative promoter and a likely muscle-speci®c regulatory region. Initial comparison to the published murine Kcna7 cDNA suggested a different N-terminal sequence for the human protein, however, further analysis suggests that the original mouse sequence contained an error or an unusual polymorphism. q 2001 Elsevier Science B.V. All rights reserved. Keywords: NotI-linking clone; Gene structure; Gene mapping 1. Introduction As NotI sites are preferentially located in CpG islands (Bird, 1987), the sequences ¯anking NotI sites can aid in the identi®cation of the edges of genes. This localization to CpG islands adjoining and within genes has resulted in the discovery of a number of new genes from the NotI clone sequencing efforts (Kashuba et al., 1999; Zabarovsky et al., 2000). Here we report the cloning of a novel, putative member of the human voltage-gated potassium channel protein family, the potassium channel gene Kv1.7 (KCNA7), originally identi®ed from a partial exon sequence in the NotI human genomic sequence collection. Potassium channels, the largest sub-family of the ion channel superfamily, play important roles in a wide variety of cells. Members of this channel family play critical roles in cellular signalling processes regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume regulation. K 1 channels are membrane± spanning proteins that selectively conduct K 1 ions across the cell membrane. Membrane depolarization activates voltage-gated potassium channels that, once opened, conduct potassium ions along the concentration gradient against the electric ®eld. This outward current leads to repo- larization of the membrane. To accomplish this, K 1 chan- nels are endowed with a set of features: (1) a water-®lled permeation pathway (pore) that allows K 1 ions to ¯ow across the cell membrane; (2) a selectivity ®lter that speci- ®es K 1 ions as permeate ion species; (3) a gating mechan- Gene 268 (2001) 115±122 0378-1119/01/$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. PII: S0378-1119(01)00423-1 www.elsevier.com/locate/gene Abbreviations: BAC, bacterial arti®cial chromosome; EST, expressed sequence tag; FISH, ¯uorescence in situ hybridization; ORF, open reading frame; PCR, polymerase chain reaction; RACE, rapid ampli®cation of cDNA ends * Corresponding author. Tel.: 146-8-728-67-37; fax: 146-8-31-94-70. E-mail address: vlakas@ki.se (V.I. Kashuba). 1 These authors contributed equally to this work.