Figure 5. Conceptual model of regulated proteins in a T. heimii cell.

The regulated proteins involved in ion transport and C_i acquisition are shown on their putative locations [39], [49], [57] . Proteins involved in vacuolar Ca²⁺ and H⁺ transport include P-type Ca²⁺ ATPases (P-ATPase), Ca²⁺/Na⁺ exchangers (NCX), Ca²⁺/H⁺ antiporters (VCX), and vacuolar H⁺ ATPases (V-ATPase). Active uptake of HCO₃ ⁻ may occur via a SLC4 family anion exchanger (AE) or an SLC26 family SO₄ ^3−/HCO₃ ^−/C₂O₄ ²⁻ anion exchanger (SAT-1). Carbonic anhydrases (CA) are located intracellularly or extracellularly and enhance the interconversion between CO₂ and HCO₃ ⁻.