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A novel voltage-gated potassium ion channel gene (Kv5.1): Molecular cloning and characterization

1994; Elsevier BV; Volume: 55; Linguagem: Inglês

1537-6605

Kirk W. Beisel, N.C. Lofton, Philip M. Kelley,

RNA Research and Splicing

Voltage-activated potassium channels comprise a family of genes which play a role in the electrophysiological properties of neurosensory and neuronal tissue. We have recently identified a novel voltage-gated potassium ion channel (designated as Kv5.1) using the both RT-PCR with degenerative oligodeoxynucleotide primers and dideoxy sequence analyses. A full length sequence of the mature transcript was obtained by mRNA walking using gene-specific oligodeoxynucleotide primers. The deduced amino acid sequence suggested that this protein has six hydrophobic membrane spanning regions (S1-S6) and an ion-selective pore (P or H5) located between S5 and S6. This structural motif is found in other members of this gene family. Kv5.1 has an amino acid sequence homology of 55% with the Shab gene, Kv2.1, within the N-terminus and the membrane spanning regions. No sequence homology was found for the C-terminus. Northern analysis using mRNA isolated from a panel of rat tissues demonstrated that a 2.4 kb message was expressed in heart and cochlear tissue. Because of the low sequence homology and the unique tissue distribution, we have tentatively assigned the Kv5.1 gene as a new subfamily. Both the rat and human homologues were sequenced and the nucleotide and amino acid homologies were 88% and 96%, respectively. Inmore » the rat, the open reading frame encodes a 540-amino acid protein with a predicted molecular mass of 61,781 daltons. Interestingly, the human homologue is truncated by 83 residues in the C-terminus by a stop codon. We have recently isolated a human genomic {lambda} clone which contains the entire human gene and are now determining chromosomal location of Kv5.1 by in situ hybridization and PCR analysis of DNA from a panel of somatic cell hybrids.« less