mTOR-regulated phosphorylation of electrogenic sodium bicarbonate cotransporter 1, NBCe1, at S255-257 regulates NBCe1 functional expression in mouse cortical astrocyte

The electrogenic sodium bicarbonate cotransporter 1, NBCe1 (SLC4A4), is the major bicarbonate transporter expressed in astrocytes. It is highly sensitive for bicarbonate, and the main regulator of intracellular-, extracellular-, and synaptic pH, thereby modulating neuronal excitability. However, despite these essential functions, the molecular mechanisms underlying NBCe1-mediated astrocytic response to extracellular pH changes are mostly unknown. Using primary cortical astrocyte cultures we have investigated the effect of long-term extracellular metabolic alkalosis on regulation of NBCe1 using functional assays and phosphoproteomic analysis.