Pharmacological characteristics of Kv1.1- and 1.2-containing channels are influenced by the stoichiometry and positioning of their {alpha} subunits

Voltage-sensitive neuronal Kv1 channels, composed of 4 a subunits and 4 associated auxiliary β subunits, control neuronal excitability and neurotransmission. Limited information exists on the combinations of a subunit isoforms (i.e. Kv1.1-1.6) or their positions in the oligomers, and how these affect sensitivity to blockers. It is known that tetraethylammonium (TEA) inhibits Kv1.1 channel largely due to binding a critical tyrosine (Y379) in the pore, whereas V381 at the equivalent location in Kv1.2 makes it insensitive. With the eventual aim of developing blockers for therapeutic purposes, Kv1.1 and 1.2 a subunit genes were concatenated to form combinations representing those in central neurons, followed by surface expression in HEK-293 cells as single-chain, functional proteins. Patch-clamp recordings demonstrated the influences of the ratios and positioning of these α subunits on the biophysical and pharmacological properties of oligomeric K+ channels. Raising the ratio of Kv1.1 to Kv1.2 in Kv1.2-1.2-1.1-1.2 led to the resultant channels being more sensitive to TEA and, also, affected their biophysical parameters. Moreover, mutagenesis of one or more residues in the first Kv1.2 to resemble those in Kv1.1 increased TEA sensitivity only when it is adjacent to a Kv1.1 subunit, whereas placing a non-interactive subunit between these two diminished susceptibility. These findings support the possibility of α subunits being precisely arranged in Kv1 cha...
Source: BJ Cell - Category: Biochemistry Authors: Tags: BJ Cell Source Type: research