Cloning and functional characterization of a sodium-dependent phosphate transporter expressed in human lung and small intestine

Biochem Biophys Res Commun. 1999 May 19;258(3):578-82. doi: 10.1006/bbrc.1999.0666.


A cDNA clone with 53% amino acid identity to the human type II sodium-dependent phosphate transporter (NaPi-3) was isolated from human small intestine and lung. Functional characterization in Xenopus laevis oocytes showed this cDNA to encode a sodium-dependent phosphate transporter. The electrogenic response is similar to that found in other type II transporters but an inverse pH dependence was observed. By Northern blot, a 4.2-kb transcript was found to be abundantly expressed in lung and, to a lesser degree, in several other tissues of epithelial origin including small intestine, pancreas, prostate, and kidney. This transcript encompasses a 2.073-kb open reading frame which is most closely related (78% amino acid identity) to the mouse sodium-dependent phosphate transporter IIb isoform. This novel transporter, designated human NaPi-3b (Genbank AF111856), appears to be an isoform of the mammalian renal type II co-transporter family.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Blotting, Northern
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cloning, Molecular
  • DNA, Complementary
  • Humans
  • Hydrogen-Ion Concentration
  • Intestine, Small / metabolism*
  • Lung / metabolism*
  • Molecular Sequence Data
  • Oocytes / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Amino Acid
  • Sodium-Phosphate Cotransporter Proteins
  • Sodium-Phosphate Cotransporter Proteins, Type II
  • Symporters*
  • Xenopus


  • Carrier Proteins
  • DNA, Complementary
  • Sodium-Phosphate Cotransporter Proteins
  • Sodium-Phosphate Cotransporter Proteins, Type II
  • Symporters

Associated data

  • GENBANK/AF111856