Bicarbonate transport in cell physiology and disease

The family of mammalian bicarbonate transport proteins are involved in a wide-range of physiological processes. The importance of bicarbonate transport follows from the biochemistry of HCO₃⁻ itself. Bicarbonate is the waste product of mitochondrial respiration. HCO₃⁻ undergoes pH-dependent conversion into CO₂ and in doing so converts from a membrane impermeant anion into a gas that can diffuse across membranes. The CO₂–HCO₃⁻ equilibrium forms the most important pH buffering system of our bodies. Bicarbonate transport proteins facilitate the movement of membrane-impermeant HCO₃⁻ across membranes to accelerate disposal of waste CO₂, control cellular and whole-body pH, and to regulate fluid movement and acid/base secretion. Defects of bicarbonate transport proteins manifest in diseases of most organ systems. Fourteen gene products facilitate mammalian bicarbonate transport, whose physiology and pathophysiology is discussed in the present review.