Subunit composition of minK potassium channels

KW Wang, SAN Goldstein - Neuron, 1995 - cell.com
KW Wang, SAN Goldstein
Neuron, 1995cell.com
Expression of minK protein in Xenopus oocytes induces a slowly activating, voltage-
dependent, potassium-selective current. Point mutations in minK that alter current gating
kinetics, ion selectivity, pharmacology, and response to protein kinase C all support the
notion that minK is a structural protein for a channel-type transporter. Yet, minK has just 130
amino acids and a single transmembrane domain. Though larger cloned potassium
channels form functional channels through tetrameric subunit association, the subunit …
Summary
Expression of minK protein in Xenopus oocytes induces a slowly activating, voltage-dependent, potassium-selective current. Point mutations in minK that alter current gating kinetics, ion selectivity, pharmacology, and response to protein kinase C all support the notion that minK is a structural protein for a channel-type transporter. Yet, minK has just 130 amino acids and a single transmembrane domain. Though larger cloned potassium channels form functional channels through tetrameric subunit association, the subunit composition of minK is unknown. Subunit stoichiometry was determined by coexpression of wildtype minK and a dominant lethal point mutant of minK, which reaches the plasma membrane but passes no current. The results support a model for complete minK potassium channels in which just two minK monomers are present, with other, as yet unidentified, non-minK subunits.
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