The study characterizes YORK, a novel yeast K+ channel with two pore domains, demonstrating unique outward rectification and gating properties intrinsic to the protein.
Answers are grounded in this paper and cite their sources.
YORK characterization offers no clinical implications now; leaves open whether its properties extend to mammalian cardiac two-pore K channels.
YORK is a newly cloned K+ channel from yeast. Unlike all other cloned K+ channels, it has two pore domains instead of one. It displays eight transmembrane segments arranged like a covalent assembly of a Shaker-type voltage-dependent K+ channel (without S4 transmembrane segments) with an inward rectifier K+ channel. When expressed in Xenopus oocytes, YORK does not pass inward currents; it conducts only K+-selective outward currents. However, the mechanism responsible for this strict outward rectification is unusual. Like inward rectifiers, its activation potential threshold closely follows the K+ equilibrium potential. Unlike inward rectifiers, the rectification is not due to a voltage-dependent Mg2+ block. The blocking element is probably intrinsic to the YORK protein itself. YORK activity is decreased at acidic internal pH, with a pKa of 6.5. Pharmacological and regulation properties were analyzed. Ba2+ ions and quinine block YORK currents through high and low affinity sites, while tetraethylammonium displays only one affinity for blocking. Activation of protein kinase C indirectly produces an increase of the current, while protein kinase A activation has no effect.
No takes yet. Share an insight, caveat, or question.
Lesage et al. (1996) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: