Effective diameter and structural organization of reconstituted calcium channels from the Characeae algae Nitellopsis

Membr Cell Biol. 1998;12(1):79-88.

Abstract

Using hydrophilic non-electrolytes, we determined the effective diameter of calcium channels from the Characeae alga Nitellopsis, reconstituted in a planar lipid membrane. It is suggested that a "single" reconstituted channel is a cluster consisting of several protochannels, in which the channel-forming molecules are stabilized by calcium ions. It is shown that the channels assembled in a cluster with the common conductivity of 350 pS (in 0.1 M KCl) have a funnel-like structure. The diameter of the smaller section is 0.96 +/- 0.20 nm, the diameter of the wider vestibule is 1.78 +/- 0.30 nm. Similarity of the structural organization of the channels investigated to the channels formed by annexin proteins is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Calcium Channels / isolation & purification
  • Calcium Channels / ultrastructure*
  • Eukaryota / metabolism*
  • Lipid Bilayers
  • Macromolecular Substances
  • Plant Proteins / isolation & purification
  • Plant Proteins / ultrastructure*

Substances

  • Calcium Channels
  • Lipid Bilayers
  • Macromolecular Substances
  • Plant Proteins