Characterization of the chicken small intestine type IIb sodium phosphate cotransporter.
Intestinal absorption and renal resorption play a critical role in overall phosphorus homeostasis in chickens. Using RNase-ligase-mediated rapid amplification of cDNA ends PCR, we obtained a cDNA from the broiler small intestine that encodes a type IIb Na-dependent phosphate transporter. The cDNA has an open reading frame of 2,022 bp and predicts a 674-amino acid protein with a molecular mass of approximately 74 kDa. Prediction of membrane spanning domains based on the hydrophilic and hydrophobic properties of the amino acids suggests 8 transmembrane domains, with both the NH(2) and COOH termini being intracellular. The Na-inorganic phosphate (Pi) IIb cotransporter has relative high homology with other type II Na-Pi cotransporters but low homology with the type I or type III Na-Pi cotransporters. Northern blot analysis demonstrated the presence of a single mRNA transcript present predominantly in the small intestine, with the highest expression in the duodenum, followed by the jejunum and ileum. In situ hybridization indicated that the Na-Pi cotransporter mRNA is expressed throughout the vertical cryptvillus axis of the small intestine. Reduction of P in the diet of chicks from hatch to 4 d of age resulted in a significant induction of Na-Pi cotransporter mRNA expression in the small intestine. Further study is needed to elucidate its physiological role in intestinal phosphate absorption in chickens.
Yan
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F
Department of Animal and Avian Sciences, University of Maryland, College Park 20742, USA.
Angel
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R
Ashwell
C M
CM
D000595:Amino Acid Sequence; D000821:Animal Feed; D000818:Animals; D001483:Base Sequence; D002645:Chickens / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004032:Diet / Q000662:veterinary; D005786:Gene Expression Regulation; D016678:Genome; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism*; D008969:Molecular Sequence Data; D016226:Phosphorus, Dietary / Q000378:metabolism / Q000494:pharmacology; D040641:Quantitative Trait Loci; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D016226:Phosphorus, Dietary; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb