A carboxylate transporter is a membrane transport protein that transports carboxylate.

They are responsible for the reabsorption of filtered carboxylate in renal physiology

Renal physiology

Renal physiology is the study of the physiology of the kidney. This encompasses all functions of the kidney, including reabsorption of glucose, amino acids, and other small molecules; regulation of sodium, potassium, and other electrolytes; regulation of fluid balance and blood pressure;...

, resulting in a 100% reabsorption in the proximal tubule

Proximal tubule

The proximal tubule is the portion of the duct system of the nephron of the kidney which leads from Bowman's capsule to the loop of Henle.-Structure and appearance:...

.

In proximal tubule

In the renal proximal tubule

Proximal tubule

The proximal tubule is the portion of the duct system of the nephron of the kidney which leads from Bowman's capsule to the loop of Henle.-Structure and appearance:...

, there are several kinds of carboxylate transporters in the apical membrane and the basolateral membrane.

Apical

• Na
  Sodium
  Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
  
  -monocarboxylate cotransporter
• 3Na-dicarboxylate cotransporter
• 3Na-tricarboxylate cotransporter

Basolateral

• H
  Hydrogen
  Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
  
  -monocarboxylate cotransporter
• organic anion-dicarboxylate exchanger