Referenced in: none

Automatically associated channels: Kir2.1

Title: Determination of the subunit stoichiometry of an inwardly rectifying potassium channel.

Authors: J Yang, Y N Jan, L Y Jan

Journal, date & volume: Neuron, 1995 Dec , 15, 1441-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8845166

Abstract
Inwardly rectifying K+ channels are distantly related to their voltage-gated counterparts and possess a structural motif of only two putative transmembrane segments in each subunit. They are formed by the assembly of an unknown number of subunits. We have examined the subunit stoichiometry of a strongly rectifying K+ channel, IRK1, by linking together the coding sequence of three or four subunits and distinguishing channels with different numbers of subunits carrying a double mutation that alters inward rectification and single-channel properties. We find that IRK1 channels, like voltage-gated K+ channels, are tetrameric channels. Interestingly, the high sensitivity to Mg2+ and polyamines, cations that produce inward rectification by blocking the channel pore from the cytoplasmic side is largely retained in a channel containing only one wild-type subunit and three subunits bearing mutations that abolish high affinity Mg2+ and polyamine block.