Cloning and functional expression of a Na(+)-dependent phosphate co-transporter from human kidney: cDNA cloning and functional expression

Biochem J. 1995 Jan 1;305 ( Pt 1)(Pt 1):81-5. doi: 10.1042/bj3050081.


A cDNA clone encoding a protein 69% identical in amino acid sequence with that of the Na/P(i) co-transporter NaP(i)-1 was isolated from a human kidney cDNA library. The DNA sequence was identical with that of NPT-1 cDNA published by Chong, Kristjansson, Zoghbi and Hughe (1993) (Genomics, 18, 355-359). In the present study, we have characterized the function of the encoded protein and the tissue distribution of its mRNA. Injection of RNA transcribed from NPT-1 into Xenopus oocytes resulted in expression of Na/P(i) co-transport activity showing a high affinity for P(i) transport (Km 0.29 mM). Kinetic characterization ([P(i)], [Na+]) demonstrated that the expressed transport activity has properties similar to those displayed by oocytes injected with human kidney poly(A)+ RNA. Northern blotting demonstrated that NPT-1 mRNA is expressed in renal cortex, liver and brain but not in other tissues. Hybrid depletion with antisense oligonucleotides to NaP(i)-3 and NPT-1 completely inhibited poly(A)+ RNA-induced Na(+)-dependent P(i) uptake in oocytes. These findings indicate that two high-affinity Na/P(i) cotransporters (NaP(i)-3 and NPT-1) are present in human kidney cortex.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Blotting, Northern
  • Carrier Proteins / genetics*
  • Carrier Proteins / physiology*
  • Cloning, Molecular
  • DNA, Complementary / genetics*
  • DNA, Complementary / isolation & purification
  • DNA, Complementary / physiology*
  • Female
  • Genomic Library
  • Humans
  • Kidney Cortex / chemistry*
  • Kidney Cortex / physiology*
  • Kinetics
  • Molecular Sequence Data
  • Oligonucleotides, Antisense / pharmacology
  • Phosphates / pharmacokinetics
  • Polymerase Chain Reaction
  • RNA, Complementary / analysis
  • RNA, Complementary / genetics
  • RNA, Messenger / analysis
  • RNA, Messenger / drug effects
  • RNA, Messenger / genetics
  • Rabbits
  • Sodium / pharmacokinetics
  • Sodium / pharmacology
  • Sodium-Phosphate Cotransporter Proteins
  • Sodium-Phosphate Cotransporter Proteins, Type I
  • Symporters*
  • Xenopus laevis


  • Carrier Proteins
  • DNA, Complementary
  • Oligonucleotides, Antisense
  • Phosphates
  • RNA, Complementary
  • RNA, Messenger
  • SLC17A1 protein, human
  • Sodium-Phosphate Cotransporter Proteins
  • Sodium-Phosphate Cotransporter Proteins, Type I
  • Symporters
  • Sodium

Associated data

  • GENBANK/D28532