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. Author manuscript; available in PMC: 2021 Jan 8.
Published in final edited form as: Calcif Tissue Int. 2019 Nov 25;108(1):16–31. doi: 10.1007/s00223-019-00636-8

Fig. 4.

Fig. 4

Cellular mechanism of Pi reabsorption in the proximal tubule. The majority of filtered Pi is reabsorbed by the electrogenic NaPi-IIa transporter in the apical membrane and depend on the basolateral Na+/K+-ATPase activity to maintain the Na+ gradient that drives the secondary active transport process. Electroneutral NaPi-IIc and electrogenic PiT-2 transporter also contribute to the apical Pi influx. Basolateral Pi efflux possibly occur by facilitated diffusion through XPR1.

Abbreviation: XPR1, xenotropic and polytropic retrovirus receptor 1