Molecular cloning, functional characterization, tissue distribution, and chromosomal localization of a human, small intestinal sodium-phosphate (Na+-P-i) transporter (SLC34A2)

Phosphate plays a crucial role in cellular metabolism, and its homeostatic regulation in intestinal and renal epithelia is critical, Apically expresse d sodium-phosphate (Na+-P-i) transporters play a critical role in this regu lation. We have isolated a cDNA (HGMW-approved symbol SLC34A2) encoding a n ovel human small intestinal Na+-P-i transporter. The cDNA is shown to be 41 35 bp in length with an open reading frame that predicts a 689-amino-acid p olypeptide, The putative protein has 76% homology to mouse intestinal type II Na+-P-i transporter (Na/Pi-IIb) and lower homologies with renal type II Na+-P-i transporters. Northern blots showed a singular transcript of 5.0 kb in human lung, small intestine, and kidney, Computer analysis suggests a p rotein with 11 transmembrane domains and several potential posttranslationa l modification sites. Functional characterization in Xenopus laevis oocytes showed that this cDNA encodes a functional Na+-P-i transporter. Furthermor e, the gene encoding this cDNA was mapped to human chromosome 4p15.1-p15.3 by the FISH method. (C) 1999 Academic Press.