Plays a critical role in the sodium-dependent reabsorption of bile acids from the lumen of the small intestine. Plays a key role in cholesterol metabolism.
CuratedUniProtKB
According to TCDB this is a transporter from family:
Catalysis of the transfer of a solute or solutes from one side of a membrane to the other according to the reaction: bile acid(out) + Na+(out) = bile acid(in) + Na+(in).
The directed movement of substances (such as macromolecules, small molecules, ions) into, out of or within a cell, or between cells, or within a multicellular organism by means of some agent such as a transporter or pore.
J. Biol. Chem. 270, 27228-27234 (1995)[PubMed:7592981]
The ileal Na+/bile acid cotransporter plays a critical role in the reabsorption of bile acids from the small intestine. In the course of cloning and characterizing the human ileal Na+/bile acid cotransporter cDNA, a dysfunctional isoform was identified in a patient diagnosed with Crohn's disease. Expression studies using hamster-human ileal Na+/bile acid cotransporter cDNA chimeras narrowed the location of the defect to the carboxyl-terminal 94 amino acids. Comparison of the sequence of the dysfunctional isoform to that of a wild-type human ileal Na+/bile acid cotransporter genomic clone revealed a single C to T transition resulting in a proline to serine substitution at amino acid position 290. The inheritance of this mutation in the proband's family was confirmed by single-stranded conformation polymorphism analysis and DNA sequencing. In transfected COS-1 cells, the single amino acid change abolished taurocholate transport activity but did not alter the transporter's synthesis or subcellular distribution. This dysfunctional mutation represents the first known molecular defect in a human sodium-dependent bile acid transporter.
Primary bile acid malabsorption (PBAM) is an idiopathic intestinal disorder associated with congenital diarrhea, steatorrhea, interruption of the enterohepatic circulation of bile acids, and reduced plasma cholesterol levels. The molecular basis of PBAM is unknown, and several conflicting mechanisms have been postulated. In this study, we cloned the human ileal Na+/bile acid cotransporter gene (SLC10A2) and employed single-stranded conformation polymorphism analysis to screen for PBAM-associated mutations. Four polymorphisms were identified and sequenced in a family with congenital PBAM. One allele encoded an A171S missense mutation and a mutated donor splice site for exon 3. The other allele encoded two missense mutations at conserved amino acid positions, L243P and T262M. In transfected COS cells, the L243P, T262M, and double mutant (L243P/T262M) did not affect transporter protein expression or trafficking to the plasma membrane; however, transport of taurocholate and other bile acids was abolished. In contrast, the A171S mutation had no effect on taurocholate uptake. The dysfunctional mutations were not detected in 104 unaffected control subjects, whereas the A171S was present in 28% of that population. These findings establish that SLC10A2 mutations can cause PBAM and underscore the ileal Na+/bile acid cotransporter's role in intestinal reclamation of bile acids.
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.
Protein involved in the movement of sodium ions across energy- transducing cell membranes. Primary active sodium transport is coupled to an energy-yielding chemical reaction such as ATP hydrolysis. Secondary active transport utilizes the voltage and ion gradients produced by the primary transport to drive the cotransport of other ions or molecules. These may be transported in the same (symport) or opposite (antiport) direction.
Protein involved in the transport of solutes across a biological membrane in one direction, which depends on the transport of another solute in the same direction. One molecule can move up an electrochemical gradient because the movement of the other molecule is more favorable. Example: the sodium/glucose co-transport.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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