ABSTRACT
The type 2 sodium phosphate co-transporter, Npt2a (SLC34A1) is
one among three known sodium coupled phosphate transporters
responsible for the re-absorption of filtered phosphate from the
lumen of the proximal renal tubule [1-5]. This highly regulated
protein is expressed in the apical membrane of renal proximal
tubule cells and is thought to be the major protein responsible for
maintenance of total body phosphate homeostasis. In rodents, Npt2a
accounts for over 70% of proximal tubule phosphate re-absorption
[1, 6-9]. Although similar analysis has not been possible in human
subjects, several studies point toward a role for Npt2a in regulation
of serum phosphorus concentration, risk of chronic kidney disease,
and risk of cardiovascular disease [10-13]. Published literature over
the past few decades has outlined a role for pH, and specifically
for vacuolar ATPase, in the regulation of the function, expression,
and trafficking of Npt2a. This chapter will review the current status
of knowledge on the relationship between vacuolar H+-ATPase and Npt2a in renal proximal tubule.
