title: Formation of Functional Heterodimers by TREK-1 and TREK-2 Two-pore Domain Potassium Channel Subunits.
abstract: Two-pore domain (K2P) potassium channels are the major molecular correlates of the background (leak) K(+) current in a wide variety of cell types. They generally play a key role in setting the resting membrane potential and regulate the response of excitable cells to various stimuli. K2P channels usually function as homodimers, and only a few examples of heteromerization have been previously reported. Expression of the TREK (TWIK-related K(+) channel) subfamily members of K2P channels often overlaps in neurons and in other excitable cells. Here, we demonstrate that heterologous coexpression of TREK-1 and TREK-2 subunits results in the formation of functional heterodimers. Taking advantage of a tandem construct (in which the two different subunits were linked together to enforce heterodimerization), we characterized the biophysical and pharmacological properties of the TREK-1/TREK-2 current. The heteromer was inhibited by extracellular acidification and by spadin similarly to TREK-1, and its ruthenium red sensitivity was intermediate between TREK-1 and TREK-2 homodimers. The heterodimer has also been distinguished from the homodimers by its unique single channel conductance. Assembly of the two different subunits was confirmed by coimmunoprecipitation of epitope-tagged TREK-1 and TREK-2 subunits, coexpressed in Xenopus oocytes. Formation of TREK-1/TREK-2 channels was also demonstrated in native dorsal root ganglion neurons indicating that heterodimerization may provide greater diversity of leak K(+) conductances also in native tissues.
authors.affiliation: From the Department of Physiology, Semmelweis University, H-1428 Budapest, Hungary.
authors.forename: Miklós
authors.initials: M
authors.lastname: Lengyel
authors.affiliation: From the Department of Physiology, Semmelweis University, H-1428 Budapest, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Czirják
authors.affiliation: From the Department of Physiology, Semmelweis University, H-1428 Budapest, Hungary enyedi.peter@med.semmelweis-univ.hu.
authors.forename: Péter
authors.initials: P
authors.lastname: Enyedi
mesh_terms: D000818:Animals; D005727:Ganglia, Spinal / Q000378:metabolism*; D015870:Gene Expression; D017136:Ion Transport / Q000502:physiology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization / Q000502:physiology*; D014982:Xenopus laevis
chemical_list: C503445:Kcnk10 protein, mouse; D009419:Nerve Tissue Proteins; D024683:Potassium Channels, Tandem Pore Domain; C103742:potassium channel protein TREK-1
keywords: Ion channel heteromerization; KCNK10; KCNK2; electrophysiology; patch clamp; pharmacology; plasma membrane; potassium channel; ruthenium red; spadin