Effective diameter and structural organization of reconstituted calcium channels from the Characeae algae Nitellopsis.
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.
Ternovsky
V I
VI
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia. vadim@intrastore.cdc.com
Berestovsky
G N
GN
D000200:Action Potentials; D015220:Calcium Channels / Q000302:isolation & purification / Q000648:ultrastructure*; D056890:Eukaryota / Q000378:metabolism*; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D010940:Plant Proteins / Q000302:isolation & purification / Q000648:ultrastructure*
D015220:Calcium Channels; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D010940:Plant Proteins