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voltage-gated K+ A channel (K+ channel IA , ISA, IA, A type K+ channel)

Function: 1) rapidly inactivating A current. 2) control of maintained repetitive firing. 3) neuronal somatodendritic subthreshold A-type K+ current 4) component of ensemble of voltage-gated ionic currents that determine somatodendritic signal integration 5) operates in subthreshold range of membrane potentials 6) relatively fast inactivation & recovery from inactivation 7) allegedly participates in long-term potentiation 8) contributes majority of K+ current in dendrites of hippocampal CA1 pyramidal cells [3] Channel characteristics: 1) conductance: 6 +/- 0.6 pS 2) inactivated with time constant of 23 +/1 2 ms at +54 mV Structure: - consists of 4 voltage-gated K+ channel subfamily A (alpha) subunits Expression: - found on CA1 pyramidal cells. Pathology: - Abeta interferes with currents of K+ A channels, leading to increased dendritic Ca+2 influx, synaptic dysfunction & neurodegeneration [2] (putative)

Interactions

molecular events

General

voltage-gated K+ channel

Properties

QUALITIES: electrochemical potential :FORM ACTIVATION :VALUE -50 :UNIT MV TIME-CONSTANT :FORM INACTIVATION :VALUE 50 :UNITS MSEC TIME-CONSTANT :FORM RECOVERY :VALUE 10 :UNITS MSEC COMPARTMENT: plasma membrane CELL: neuron WITHIN: brain ORGANISM: vertebrate* MOTIF: membrane region ION-PERMEABILITY: K+ SUBUNITS: voltage-gated K+ channel alpha subunit (4) MOTIF: transmembrane domain (6) H5 (K+) pore-forming region ION-PERMEABILITY: K+

References

  1. Lotan I, Dascal N, Naor Z, Boton R. Modulation of vertebrate brain Na+ and K+ channels by subtypes of protein kinase C. FEBS Lett. 1990 Jul 2;267(1):25-8. PMID: 1694792
  2. Chen C beta-Amyloid increased dendritic Ca+2 influx by inhibiting the A-type K+ current in hippocampal CA1 neurons. Biochem Biophys Res Commun 2005, 338:1913 PMID: 16289381
  3. Chen X and Johnston D Properties of single voltgage-dependent K+ channels in dendrites of CA1 pyramidal neurones of rat hippocampus. J Physiol 2004, 559:187 PMID: 15218076
  4. Storm Nature 336 379 1988
  5. Jerng HH, Pfaffinger PJ, Covarrubias M. Molecular physiology and modulation of somatodendritic A-type potassium channels. Mol Cell Neurosci. 2004 Dec;27(4):343-69 PMID: 15555915

Components

voltage-gated K+ channel alpha subunit