Molecular cloning and permanent expression in a neuroblastoma cell line of a fast inactivating potassium channel from bovine adrenal medulla.
Using a cDNA library from bovine adrenal medulla, we have isolated cDNAs coding for a potassium channel. These cDNAs encode a 660-amino acid protein that has a molecular weight of 73,288 kDa and no amino-terminal signal peptide. We have called it BAK4. Analysis of its sequence reveals close similarity (94% homology) with a recently described potassium channel from rat brain (RCK4) and heart (RHK1). Neuroblastoma cells (Neuro-2a cell line) were stably transfected with BAK4 DNA. Expression of the DNA was under the control of a heat-shock promoter. Several clones, that were isolated by neomycin resistance selection, had integrated the plasmid DNA in a stable form. Upon heat induction, these cells produced BAK4 RNA and a potassium outward current, not present in control non-transfected cells. The current, which was transient and decayed markedly during the duration of 200 ms-pulses, can be described as a Ik(A) potassium current. The expression of these types of channels in brain (RCK4,RHK1), heart (RHK1) and adrenal medulla (BAK4) suggest their possible implication in important functions for the cell.
García-Guzmán
M
M
Laboratorio de Neurobiología Molecular, Universidad de Alicante, Spain.
Calvo
S
S
Ceña
V
V
Criado
M
M
D000313:Adrenal Medulla / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003001:Cloning, Molecular; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009447:Neuroblastoma; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D008565:Membrane Proteins; D015221:Potassium Channels; D011994:Recombinant Proteins; C076184:BAK4 protein, Bos taurus; D011188:Potassium