Sodium-dependent phosphate cotransporter (NaPi) (NaPi)

Sodium-dependent phosphate cotransporters are a group of membrane proteins responsible for the active transport of inorganic phosphate across cell membranes, primarily in the kidneys and intestines (Wagner et al., 2013). They are categorized into two main families: SLC34 (Type II) and SLC20 (Type III). In the kidney, NaPi-IIa (SLC34A1) and NaPi-IIc (SLC34A3) are the primary mediators of phosphate reabsorption from the glomerular filtrate, while NaPi-IIb (SLC34A2) is the major transporter for intestinal phosphate absorption (NIH, 2020). These transporters are critical for maintaining systemic phosphate homeostasis, which is essential for bone mineralization, energy metabolism, and cellular signaling (MDPI, 2023). Dysregulation of these transporters is linked to several diseases, including hyperphosphatemia in chronic kidney disease (CKD), which contributes to vascular calcification and cardiovascular mortality (NIH, 2022). Consequently, they have emerged as significant therapeutic targets; inhibitors like EOS789 and PF-06869206 are being developed to reduce phosphate levels by blocking intestinal absorption or promoting renal excretion (MedChemExpress, 2024). Additionally, NaPi-IIb is overexpressed in certain cancers, such as ovarian and lung cancer, making it a target for antibody-drug conjugates like lifastuzumab vedotin (NIH, 2019).

Other names

Phosphate transporterSodium-phosphate cotransporterType II sodium-dependent phosphate cotransporterType III sodium-dependent phosphate cotransporterSLC34SLC20NPTNPT2aNPT2bNPT2cPiT-1PiT-2

Inhibition of active transcellular phosphate transport in the intestine or kidney; downregulation of transporter expression; targeted delivery of cytotoxic agents via antibody-drug conjugates.