Molecular cloning and expression of a Kv1.1-like potassium channel from the electric organ of Electrophorus electricus.
Electrocytes from the electric organ of Electrophorus electricus exhibited sodium action potentials that have been proposed to be repolarized by leak currents and not by outward voltage-gated potassium currents. However, patch-clamp recordings have suggested that electrocytes may contain a very low density of voltage-gated K(+) channels. We report here the cloning of a K(+) channel from an eel electric organ cDNA library, which, when expressed in mammalian tissue culture cells, displayed delayed-rectifier K(+) channel characteristics. The amino-acid sequence of the eel K(+) channel had the highest identity to Kv1.1 potassium channels. However, different important functional regions of eel Kv1.1 had higher amino-acid identity to other Kv1 members, for example, the eel Kv1.1 S4-S5 region was identical to Kv1.5 and Kv1.6. Northern blot analysis indicated that eel Kv1.1 mRNA was expressed at appreciable levels in the electric organ but it was not detected in eel brain, muscle, or cardiac tissue. Because electrocytes do not express robust outward voltage-gated potassium currents we speculate that eel Kv1.1 channels are chronically inhibited in the electric organ and may be functionally recruited by an unknown mechanism.
Thornhill
W B
WB
Department of Biological Sciences, Fordham University, Bronx, NY 10458, USA. thornhill@fordham.edu
Watanabe
I
I
Sutachan
J J
JJ
Wu
M B
MB
Wu
X
X
Zhu
J
J
Recio-Pinto
E
E
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D004557:Electric Organ / Q000737:chemistry* / Q000502:physiology*; D004593:Electrophorus / Q000235:genetics / Q000378:metabolism*; D051662:Kv1.1 Potassium Channel; D008564:Membrane Potentials / Q000502:physiology*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014018:Tissue Distribution; D014982:Xenopus laevis
D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011994:Recombinant Proteins; D051662:Kv1.1 Potassium Channel; D011188:Potassium