Cation Chloride Cotransporter 1 (CCC1) regulates pH and ionic conditions in the TGN/EE and is required for endomembrane trafficking

Abstract

The secretory and endocytic pathways intersect at the Trans-Golgi Network/Early Endosome (TGN/EE). TGN/EE function depends on luminal pH adjustment, which is regulated by the combined activity of a proton pump and several proton/ion antiporters. The identity of the proton pump is known, as well the antiporters that catalyse cation and anion import into the TGN/EE. However, the protein(s) required to complete the transport circuit, and that mediates cation and anion efflux has not been identified. Here, we characterise Arabidopsis Cation Chloride Cotransporter (AtCCC1) and show that it is localised in the TGN/EE. We further demonstrate that regulation of both luminal pH and ion concentrations..