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Molecular cloning and functional characterization of a novel delayed rectifier potassium channel from channel catfish ( Ictalurus punctatus ): expression in taste buds
Author(s) -
Kang Jiesheng,
Teeter John H.,
Brazier Stephen P.,
Nguyen Nguyen D.,
Chang Christine C.,
Puchalski Ralph B.
Publication year - 2001
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2001.00137.x
Subject(s) - catfish , ictalurus , biology , xenopus , subfamily , potassium channel , complementary dna , peptide sequence , biochemistry , microbiology and biotechnology , gene , endocrinology , fishery , fish <actinopterygii>
The gustatory system of channel catfish is widely studied for its sensitivity to amino acids. As a first step in identifying the molecular components that play a role in taste transduction in catfish, we cloned the full‐length cDNA for Kv2‐catfish, a novel K + channel that is expressed in taste buds. The deduced amino acid sequence is 816 residues, and shares a 56–59% sequence identity with Kv2.1 and Kv2.2, the other members of the vertebrate Kv2 subfamily of voltage‐gated K + channels. The Kv2‐catfish RNA was expressed in taste buds, brain, skeletal muscle, kidney, intestine and gills, and its gene is represented as a single copy in the catfish genome. Recombinant channels expressed in Xenopus oocytes were selective for K + , and were inhibited by tetraethylammonium applied to the extracellular side of the membrane during two‐electrode voltage clamp analysis with a 50% inhibitory constant of 6.1 m m . The channels showed voltage‐dependent activation, and did not inactivate within 200 ms. Functionally, Kv2‐catfish is a voltage‐gated, delayed rectifier K + channel, and its primary structure is the most divergent sequence identified among the vertebrate members of the Kv2 subfamily of K + channels, being related equally well to Kv2.1 and Kv2.2.