| Regulation of intestinal Na+-dependent phosphate co-transporters by a low-phosphate diet and 1,25-dihydroxyvitamin D3. | |
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MedLine Citation:
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PMID: 10527952 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In a study of the rat intestinal P(i) transport system, an activator protein for rat Na/P(i) co-transport system (PiUS) was isolated and characterized. We also investigated the effects of restriction of vitamin D and P(i) (two of the most important physiological and pathophysiological regulators of P(i) absorption in the small intestine) on intestinal P(i) transport activity and the expression of Na/P(i) co-transporters that are expressed in rat small intestine. Rat PiUS encodes a 424-residue protein with a calculated molecular mass of 51463 Da. The microinjection of rat PiUS into Xenopus oocytes markedly stimulated Na(+)-dependent P(i) co-transport activity. In rats fed with a low-P(i) diet, Na(+)-dependent P(i) co-transport activity was increased approx. 2-fold compared with that of rats fed a normal P(i) diet. Kinetic studies demonstrated that this increased activity was due to an elevation of V(max) but not K(m). The PiUS mRNA levels showed an approximate doubling in the rats fed with the low-P(i) diet compared with those fed with the normal P(i) diet. In addition, after the administration of 1, 25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] to vitamin D-deficient animals, the P(i) uptake was significantly increased in the Na(+)-dependent component in the brush border membrane vesicle (BBMV) at 24 and 48 h. In addition, we found a further high-affinity Na/P(i) co-transport system in the BBMV isolated from the vitamin D-replete animals. The levels of type III Na/P(i) co-transporter PiT-2 mRNA were increased 24 and 48 h after 1,25-(OH)(2)D(3) administration to vitamin D-deficient animals, whereas PiUS and the type IIb Na/P(i) co-transporter mRNA levels were unchanged. In conclusion, we first cloned a rat activator protein, PiUS, and then studied its role along with that of other type III Na/P(i) co-transporters. PiUS and PiT-2 might be important components in the regulation of the intestinal P(i) transport system by P(i) restriction and 1,25-(OH)(2)D(3). |
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Authors:
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K Katai; K Miyamoto; S Kishida; H Segawa; T Nii; H Tanaka; Y Tani; H Arai; S Tatsumi; K Morita; Y Taketani; E Takeda |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Biochemical journal Volume: 343 Pt 3 ISSN: 0264-6021 ISO Abbreviation: Biochem. J. Publication Date: 1999 Nov |
Date Detail:
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Created Date: 2000-01-03 Completed Date: 2000-01-03 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2984726R Medline TA: Biochem J Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 705-12 Citation Subset: IM |
Affiliation:
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Department of Clinical Nutrition, School of Medicine, Tokushima University, Kuramoto-Cho 3, Tokushima City, Tokushima 770, Japan. |
| Data Bank Information | |
Bank Name/Acc. No.:
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GENBANK/AB015723 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acid Sequence Animals Base Sequence Calcitriol / pharmacology* Carrier Proteins / chemistry, genetics*, metabolism* Female Gene Expression Regulation / drug effects, physiology* Intestinal Mucosa / metabolism* Jejunum / physiology* Kinetics Male Microvilli / drug effects, metabolism Molecular Sequence Data Oocytes / physiology Phosphates / administration & dosage, metabolism*, pharmacology* Phosphorus, Dietary / pharmacology* Rats Rats, Wistar Recombinant Proteins / metabolism Sodium-Phosphate Cotransporter Proteins Sodium-Phosphate Cotransporter Proteins, Type IIb Symporters* Transcription, Genetic* / drug effects Vitamin D Deficiency / metabolism Xenopus laevis |
| Chemical | |
Reg. No./Substance:
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0/Carrier Proteins; 0/Phosphates; 0/Phosphorus, Dietary; 0/Recombinant Proteins; 0/Slc34a2 protein, rat; 0/Sodium-Phosphate Cotransporter Proteins; 0/Sodium-Phosphate Cotransporter Proteins, Type IIb; 0/Symporters; 32222-06-3/Calcitriol |
| Comments/Corrections | |
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