Figure 1

Urate transporters at the proximal tubule. Transporters responsible for urate reabsorption and secretion are illustrated [18, 21, 43, 48, 52, 77–80]. Sodium-anion co-transporters SMCT1 and 2 at the apical membrane are included in this figure because SMCT transports lactate, the counterpart of urate. URAT1 is a main transporter for urate reabsorption in exchange for lactate at the apical membrane. URAT1 mediates the exchange of urate for several organic anions and inorganic anions. The long isoform of GLUT9 (GLUT9L) is localized to basolateral membranes in proximal tubule epithelial cells, while the short splice variant (GLUT9S) localizes to apical membranes. GLUT9L is a primary efflux transporter of intracellular urate to the interstitium/blood space. Abbreviations: ABCG2, ATP-binding cassette, sub-family G, member 2; α-KG, α-ketoglutarate; CsA, cyclosporine A; ES, estrone sulfate; GLUT, glucose transporter; MRP4, multidrug resistance protein 4; NPT1, sodium-dependent phosphate transport protein 1; OAT, organic anion transporter; PAH, paraaminohippurate; SMCT, sodium-coupled monocarboxylate transporter; URAT1: urate transporter 1.