Molecular properties of Kcv, a virus encoded K+ channel

Biochemistry. 2007 Jan 30;46(4):1079-90. doi: 10.1021/bi061530w.


The miniature viral K+ channel Kcv represents the pore module of all K+ channels. A synthetic gene of Kcv with an elevated GC content compared to that of the wild-type gene was expressed heterologously in Pichia pastoris, and the purified protein was functionally reconstituted into liposomes. Biochemical assays reveal a remarkable cation selective stability of the channel tetramer via SDS-PAGE. Only cations, which permeate Kcv, were able to protect the oligomer against disassembly into monomers at high temperatures. Electrophysiological characterization of the single Kcv channel reveals a saturating conductance (lambda(max)) of 360 pS; the single-channel current-voltage relation was strongly rectifying with a negative slope conductance at extreme voltages. The channel was highly selective for K+ and was blocked by Ba2+ and in a side specific manner by Na+ and Cs+ also. The channel conducted Rb+, but as a consequence, the channel was shifted into a hyperactive state. We conclude that specific binding interactions of cations in the conductive pathway are an important determinant of channel stability and function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Barium / pharmacology
  • Base Sequence
  • Cations, Monovalent / pharmacology
  • Cesium / pharmacology
  • DNA, Viral / genetics
  • Electric Conductivity
  • Gene Expression
  • Genes, Viral
  • Molecular Sequence Data
  • Phycodnaviridae / genetics
  • Phycodnaviridae / metabolism*
  • Pichia / genetics
  • Potassium Channel Blockers / pharmacology
  • Potassium Channels / chemistry*
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Protein Structure, Quaternary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Viral Proteins / antagonists & inhibitors
  • Viral Proteins / chemistry*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*


  • Cations, Monovalent
  • DNA, Viral
  • Kcv potassium channel, Chlorella virus
  • Potassium Channel Blockers
  • Potassium Channels
  • Recombinant Proteins
  • Viral Proteins
  • Cesium
  • Barium