KCa4.2 channels

Channel KCa4.2
Description Sodium-activated potassium channel gated by voltage, internal Na+ and Cl-, and inhibited by ATP
Other names Slick, Slo2.1, KCNT2
Molecular information Human: 1138aa, NM_198503; chr. 1q31.3, KCNT2
Mouse: 1131aa, XM_136252, chr. 1
Rat: 1142aa, NM_198762, chr. 13q13
Associated subunits No β-subunits identified; binding to PSD-95 scaffolding protein via first PDZ domain4
Functional Assays Voltage-clamp, patch-clamp
Current K+-selective
Conductance 141pS (130 mM symmetric K+), multiple subconductance states1
Ion Selectivity K+-selective
Activation Gated by voltage (weakly voltage-sensitive) and synergistically by internal Na+ and Cl- (5-fold increase in NPo when Na+ raised from 1–100 mM, with 30 mM Cl-; 5-fold increase in NPo when Cl- raised from 3–130 mM, with 5 mM Na+)1
Inactivation None
Activators None
Blockers TEA, >60% block by 20 mM; quindine, >90% block by 1.0 mM1
Gating inhibitors Intracellular ATP, >80% block by 5.0 mM
Radioligands None
Channel distribution Ubiquitous (mouse Slo2.1)5; brain (olfactory bulb, supraoptic nucleus, hippocampus, somatosensory and visual cortex, thalamus, deep cerebellar nucleus, oculomotor nucleus, auditory nuclei), heart2 (rat Slick); neuronal immunohistochemical staining observed in cell bodies and axonal tracts
Physiological functions Not established
Mutations and pathophysiology Not established; C. elegans slo-2 loss-of-function mutants are hypersensitive to hypoxic death4,5
Pharmacological significance Not established; native KNa channels proposed to protect against hypoxic insult in cardiac muscles3
  • aa, amino acids; chr., chromosome; PDZ, postsynaptic density 95/disc-large/zona occludens; TEA, tetraethylammonium.

  • 1. Bhattacharjee A, Gan L, and Kaczmarek LK (2002) Localization of the Slack potassium channel in the rat central nervous system. J Comp Neurol 454:241-254

  • 2. Bhattacharjee A, Joiner WJ, Wu M, Yang Y, Sigworth FJ, and Kaczmarek LK (2003) Slick (Slo2.1), a rapidly-gated sodium-activated potassium channel inhibited by ATPJ. Neurosci 23:11681-11691

  • 3. Kameyama M, Kakei M, Sato R, Shibasaki T, Matsuda H, and Irisawa H (1984) Intracellular Na+ activates a K+ channel in mammalian cardiac cells. Nature (Lond) 309:354-356

  • 4. Yuan A, Dourado M, Butler A, Walton N, Wei A, and Salkoff L (2000) SLO-2, a K+ channel with an unusual Cl- dependence Nat Neurosci 3:771-779

  • 5. Yuan A, Santi CM, Wei A, Wang Z-W, Pollak K, Nonet M, Kaczmarek L, Crowder CM, and Salkoff L (2003) The sodium-activated potassium channel is encoded by a member of the Slo gene family. Neuron 37:765-773