[HTML][HTML] GOLAC: an endogenous anion channel of the Golgi complex

MH Nordeen, SM Jones, KE Howell, JH Caldwell - Biophysical Journal, 2000 - cell.com
MH Nordeen, SM Jones, KE Howell, JH Caldwell
Biophysical Journal, 2000cell.com
The Golgi complex is present in every eukaryotic cell and functions in posttranslational
modifications and sorting of proteins and lipids to post-Golgi destinations. Both functions
require an acidic lumenal pH and transport of substrates into and by-products out of the
Golgi lumen. Endogenous ion channels are expected to be important for these features, but
none has been described. Ion channels from an enriched Golgi fraction cleared of transiting
proteins were incorporated into planar lipid bilayers. Eighty percent of the single-channel …
Abstract
The Golgi complex is present in every eukaryotic cell and functions in posttranslational modifications and sorting of proteins and lipids to post-Golgi destinations. Both functions require an acidic lumenal pH and transport of substrates into and by-products out of the Golgi lumen. Endogenous ion channels are expected to be important for these features, but none has been described. Ion channels from an enriched Golgi fraction cleared of transiting proteins were incorporated into planar lipid bilayers. Eighty percent of the single-channel recordings revealed the same anion channel. This channel has novel properties and has been named GOLAC (Golgi anion channel). The channel has six subconductance states with a maximum conductance of 130pS, is open over 95% of the time, and is not voltage-gated. Significant for Golgi function, the channel conductance is increased by reduction of pH on the lumenal surface. This channel may serve two nonexclusive functions: providing counterions for the acidification of the Golgi lumen by the H+-ATPase and removal of inorganic phosphate generated by glycosylation and sulfation of proteins and lipids in the Golgi.
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