Referenced in: none

Automatically associated channels: Kir1.1 , Kir2.1 , Kir2.3 , Kir3.1

Title: Cloning and expression of a novel human brain inward rectifier potassium channel.

Authors: E N Makhina, A J Kelly, A N Lopatin, R W Mercer, C G Nichols

Journal, date & volume: J. Biol. Chem., 1994 Aug 12 , 269, 20468-74

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8051145

Abstract
A complementary DNA encoding an inward rectifier K+ channel (HRK1) was isolated from human hippocampus using a 392-base pair cDNA (HHCMD37) as a probe. HRK1 shows sequence similarity to three recently cloned inwardly rectifying potassium channels (IRK1, GIRK1, and ROMK1, 60, 42, and 37%, respectively) and has a similar proposed topology of two membrane spanning domains that correspond to the inner core structure of voltage gated K+ channels. When HRK1 was expressed in Xenopus oocytes, large inward K+ currents were observed below the K+ reversal potential but very little outward K+ current was observed. In on-cell membrane patches, single channel conductance (g) was estimated to be 10 picosiemens by both direct measurement and noise analysis, in 102 mM external [K+]. HRK1 currents were blocked by external Ba2+ and Cs+ (K(0) = 183 microM, and K(-130) = 30 microM, respectively), and internal tetraethylammonium ion (K(0) = 62 microM), but were insensitive to external tetraethylammonium ion. The functional properties of HRK1 are very similar to those of glial cell inward rectifier K+ channels and HRK1 may represent a glial cell inward rectifier.