Figure 2

Schematic representation of the interaction between PDZ proteins and urate transporters at the apical membrane of the proximal tubule. PDZK1 binds another PDZ protein, Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1). NHERF1 contains two tandem PDZ domains and a carboxy-terminal domain that binds members of the ERM (ezrin-radixin-moesin) family of membrane-cytoskeletal adaptors. The carboxyl terminus of URAT1, OAT4, and NPT1 binds with PDZK1 [81]. URAT1 interacts with PDZK1 via PDZ domains 1, 2, and 4, while OAT4 interacts with PDZ domains 1 and 4 [56, 57]. OAT4, NPT1, and MRP4 also bind NHERF1 [82, 83]. Abbreviations: MRP4, multidrug resistance protein 4; NHERF, Na⁺/H⁺ exchanger regulatory factor; NPT1, sodium-dependent phosphate transport protein 1; OAT, organic anion transporter; URAT1, urate transporter 1.