alpha subunit compositions of Kv1.1-containing K+ channel subtypes fractionated from rat brain using dendrotoxins

Eur J Biochem. 1999 Jul;263(1):230-7. doi: 10.1046/j.1432-1327.1999.00493.x.


K+ channels from the Kv1 subfamily contain four alpha-subunits and the combinations (from Kv1.1-1.6) determine susceptibility to dendrotoxin (DTX) homologues. The subunit composition of certain subtypes in rat brain was investigated using DTXk which only interacts with Kv1.1-containing channels and alphaDTX (and its closely related homologue DTXi) that binds preferentially to Kv1. 2-possessing homo- or hetero-oligomers. Covalent attachment of [125I]DTXk bound to channels in synaptic membranes unveiled subunits of Mr = 78 000 and 96 000. Immunoprecipitation of these solubilized and dissociated cross-linked proteins with IgG specific for each of the alpha-subunits identified Kv1.1, 1.2 and 1.4; this led to assemblies of Kv1.1/1.2 and 1.1/1.4 being established. Kv1. 2-enriched channels, purified from rat brain by chromatography on immobilized DTXi, contained Kv1.1, 1.2 and 1.6 confirming one of the above-noted pairs and indicating an additional Kv1.1-containing oligomer (Kv1.1/1.2/1.6); the notable lack of Kv1.4 excludes a Kv1. 1/1.2/1.4 combination. On the other hand, channels with Kv1.1 as a constituent, isolated using DTXk, possessed Kv1.4 in addition to those found in the DTXi-purified oligomers; this provides convergent support for the occurrence of the three combinations established above but adds a possible fourth (Kv1.1/1.4/1.6), though this was not confirmed. Moreover, sequential purification on DTXi and DTXk resins yielded channels containing only Kv1.1/1.2 but with an apparent predominance of Kv1.1, reaffirming the latter multimer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Chemistry*
  • Chromatography, Affinity
  • Cross-Linking Reagents
  • Elapid Venoms* / metabolism
  • Kinetics
  • Kv1.1 Potassium Channel
  • Molecular Weight
  • Peptides / metabolism
  • Potassium Channels / chemistry*
  • Potassium Channels / isolation & purification*
  • Potassium Channels / metabolism
  • Potassium Channels, Voltage-Gated*
  • Precipitin Tests
  • Protein Conformation
  • Rats
  • Synaptic Membranes / chemistry


  • Cross-Linking Reagents
  • Elapid Venoms
  • Peptides
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • dendrotoxin K
  • Kv1.1 Potassium Channel
  • dendrotoxin