Dataset Information

Cloning and expression of a cDNA encoding a brain-specific Na(+)-dependent inorganic phosphate cotransporter.

ABSTRACT: We have isolated a brain-specific cDNA that encodes a Na(+)-dependent inorganic phosphate (Pi) cotransporter (BNPI). The nucleotide sequence of BNPI predicts a protein of 560 amino acids with 6-8 putative transmembrane-spanning segments that is approximately 32% identical to the rabbit kidney Na(+)-dependent Pi cotransporter. Expression of BNPI mRNA in Xenopus oocytes results in Na(+)-dependent Pi transport similar to that reported for the recombinantly expressed or native kidney Na(+)-dependent cotransporter. RNA blot analysis reveals that BNPI mRNA is expressed predominantly (if not exclusively) in brain, and in situ hybridization histochemistry reveals BNPI transcripts in neurons of the cerebral cortex, hippocampus, and cerebellum. Furthermore, we have confirmed the presence of saturable Na(+)-dependent Pi cotransport in cultured cerebellar granule cells. Together, these data demonstrate the presence of a specific neuronal Na(+)-dependent transport system for Pi in brain.

SUBMITTER: Ni B

PROVIDER: S-EPMC44045 | biostudies-other | 1994 Jun

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Cloning and expression of a cDNA encoding a brain-specific Na(+)-dependent inorganic phosphate cotransporter.

Ni B B Rosteck P R PR Nadi N S NS Paul S M SM

Proceedings of the National Academy of Sciences of the United States of America 19940601 12

We have isolated a brain-specific cDNA that encodes a Na(+)-dependent inorganic phosphate (Pi) cotransporter (BNPI). The nucleotide sequence of BNPI predicts a protein of 560 amino acids with 6-8 putative transmembrane-spanning segments that is approximately 32% identical to the rabbit kidney Na(+)-dependent Pi cotransporter. Expression of BNPI mRNA in Xenopus oocytes results in Na(+)-dependent Pi transport similar to that reported for the recombinantly expressed or native kidney Na(+)-dependent ...[more]

PMID: 8202535

Similar Datasets

Project description:Phosphate plays essential biological roles and its plasma level in humans requires tight control to avoid bone loss (insufficiency) or vascular calcification (excess). Intestinal absorption and renal reabsorption of phosphate are mediated by members of the SLC34 family of sodium-coupled transporters (NaPi-IIa,b,c) whose membrane expression is regulated by various hormones, circulating proteins, and phosphate itself. Consequently, NaPi-II proteins are also potentially important pharmaceutical targets for controlling phosphate levels. Their crucial role in Pi homeostasis is underscored by pathologies resulting from naturally occurring SLC34 mutations and SLC34 knockout animals. SLC34 isoforms have been extensively studied with respect to transport mechanism and structure-function relationships; however, the three-dimensional structure is unknown. All SLC34 transporters share a duplicated motif comprising a glutamine followed by a stretch of threonine or serine residues, suggesting the presence of structural repeats as found in other transporter families. Nevertheless, standard bioinformatic approaches fail to clearly identify a suitable template for molecular modeling. Here, we used hydrophobicity profiles and hidden Markov models to define a structural repeat common to all SLC34 isoforms. Similar approaches identify a relationship with the core regions in a crystal structure of Vibrio cholerae Na(+)-dicarboxylate transporter VcINDY, from which we generated a homology model of human NaPi-IIa. The aforementioned SLC34 motifs in each repeat localize to the center of the model, and were predicted to form Na(+) and Pi coordination sites. Functional relevance of key amino acids was confirmed by biochemical and electrophysiological analysis of expressed, mutated transporters. Moreover, the validity of the predicted architecture is corroborated by extensive published structure-function studies. The model provides key information for elucidating the transport mechanism and predicts candidate substrate binding sites.

Dataset Information

Cloning and expression of a cDNA encoding a brain-specific Na(+)-dependent inorganic phosphate cotransporter.

Publications

Cloning and expression of a cDNA encoding a brain-specific Na(+)-dependent inorganic phosphate cotransporter.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets