Cloning and characterization of a type III Na-dependent phosphate cotransporter from mouse intestine

Liqun Bai, James F. Collins, Fayez K. Ghishan

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Intestinal and renal absorption of inorganic phosphate (P(i)) is critical for phosphate homeostasis in mammals. We have isolated a cDNA that encodes a type III Na-dependent phosphate cotransporter from mouse small intestine (mPit-2). The nucleotide sequence of mPit-2 predicts a protein of 653 amino acids with at least 10 putative transmembrane domains. Kinetic studies, carried out in Xenopus oocytes, showed that mPit-2 cRNA induces significant Na-dependent P(i) uptake with an apparent Michaelis constant (K(m)) for phosphate of 38 μM. The transport of phosphate by mPit-2 is inhibited at high pH. Northern blot analysis demonstrated the presence of mPit-2 mRNA in various tissues, including intestine, kidney, heart, liver, brain, testis, and skin. The highest expression of mPit-2 in the intestine was found in the jejunum. In situ hybridization revealed that mPit-2 mRNA is expressed throughout the vertical crypt-villus axis of the intestinal epithelium. The presence of mPit-2 in the mouse intestine and its unique transport characteristics suggest that multiple Na-dependent cotransporters may contribute to phosphate absorption in the mammalian small intestine.

Original languageEnglish (US)
Pages (from-to)C1135-C1143
JournalAmerican Journal of Physiology - Cell Physiology
Volume279
Issue number4 48-4
StatePublished - Dec 7 2000

Keywords

  • Amphotropic routine retrovirus receptor
  • Na-P(i)-III
  • Pit-2
  • Ram-1
  • Sodium-dependent phosphate cotransporter
  • Sodium-phosphate transporter

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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