Page last updated: 2024-10-24

bile acid:sodium symporter activity

Definition

Target type: molecularfunction

Enables 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). [TC:2.A.28.-.-]

Bile acid:sodium symporter activity is a crucial process in the absorption of bile acids from the intestinal lumen into the bloodstream. This process involves the coordinated movement of bile acids and sodium ions across the apical membrane of enterocytes, the cells lining the small intestine. The transport is driven by the electrochemical gradient of sodium ions, which are actively pumped out of the enterocyte by the sodium-potassium pump. This creates a favorable gradient for sodium to enter the cell, and as it does, it brings along a bile acid molecule. The symporter protein responsible for this transport is known as the apical sodium-dependent bile acid transporter (ASBT), also called ileal bile acid transporter (IBAT).

The activity of ASBT is essential for the efficient recycling of bile acids, which are critical for the digestion and absorption of lipids. Bile acids are synthesized in the liver, conjugated with glycine or taurine, and secreted into the bile. They are then stored in the gallbladder and released into the small intestine during digestion. After their role in lipid digestion, bile acids are reabsorbed in the terminal ileum by ASBT and transported back to the liver. This process is known as enterohepatic circulation.

The molecular function of ASBT involves several steps:

1. **Binding:** ASBT binds to both bile acids and sodium ions at specific binding sites on the protein.
2. **Conformation change:** The binding of bile acids and sodium ions induces a conformational change in ASBT, causing it to open and allow both molecules to move through the membrane.
3. **Translocation:** The bile acid and sodium ion move across the membrane and are released into the cytoplasm of the enterocyte.
4. **Recycling:** After release, ASBT returns to its initial conformation, ready to bind more bile acids and sodium ions.

In summary, the molecular function of bile acid:sodium symporter activity is a tightly regulated process that ensures efficient absorption of bile acids from the gut, critical for lipid digestion and recycling. The transport is mediated by the ASBT protein, which utilizes the electrochemical gradient of sodium to facilitate the movement of bile acids across the enterocyte membrane.'
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Proteins (4)

ProteinDefinitionTaxonomy
Sodium/bile acid cotransporterA hepatic sodium/bile acid cotransporter that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q14973]Homo sapiens (human)
Ileal sodium/bile acid cotransporterAn ileal sodium/bile acid cotransporter that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q12908]Homo sapiens (human)
Sodium/bile acid cotransporterA hepatic sodium/bile acid cotransporter that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q14973]Homo sapiens (human)
Ileal sodium/bile acid cotransporterAn ileal sodium/bile acid cotransporter that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q12908]Homo sapiens (human)

Compounds (32)

CompoundDefinitionClassesRoles
furosemidefurosemide : A chlorobenzoic acid that is 4-chlorobenzoic acid substituted by a (furan-2-ylmethyl)amino and a sulfamoyl group at position 2 and 5 respectively. It is a diuretic used in the treatment of congestive heart failure.

Furosemide: A benzoic-sulfonamide-furan. It is a diuretic with fast onset and short duration that is used for EDEMA and chronic RENAL INSUFFICIENCY.
chlorobenzoic acid;
furans;
sulfonamide
environmental contaminant;
loop diuretic;
xenobiotic
avaproirbesartan : A biphenylyltetrazole that is an angiotensin II receptor antagonist used mainly for the treatment of hypertension.

Irbesartan: A spiro compound, biphenyl and tetrazole derivative that acts as an angiotensin II type 1 receptor antagonist. It is used in the management of HYPERTENSION, and in the treatment of kidney disease.
azaspiro compound;
biphenylyltetrazole
angiotensin receptor antagonist;
antihypertensive agent;
environmental contaminant;
xenobiotic
ketoconazole1-acetyl-4-(4-{[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy}phenyl)piperazine : A dioxolane that is 1,3-dioxolane which is substituted at positions 2, 2, and 4 by imidazol-1-ylmethyl, 2,4-dichlorophenyl, and [para-(4-acetylpiperazin-1-yl)phenoxy]methyl groups, respectively.dichlorobenzene;
dioxolane;
ether;
imidazoles;
N-acylpiperazine;
N-arylpiperazine
propranololpropranolol : A propanolamine that is propan-2-ol substituted by a propan-2-ylamino group at position 1 and a naphthalen-1-yloxy group at position 3.

Propranolol: A widely used non-cardioselective beta-adrenergic antagonist. Propranolol has been used for MYOCARDIAL INFARCTION; ARRHYTHMIA; ANGINA PECTORIS; HYPERTENSION; HYPERTHYROIDISM; MIGRAINE; PHEOCHROMOCYTOMA; and ANXIETY but adverse effects instigate replacement by newer drugs.
naphthalenes;
propanolamine;
secondary amine
anti-arrhythmia drug;
antihypertensive agent;
anxiolytic drug;
beta-adrenergic antagonist;
environmental contaminant;
human blood serum metabolite;
vasodilator agent;
xenobiotic
sulfasalazinesulfasalazine : An azobenzene consisting of diphenyldiazene having a carboxy substituent at the 4-position, a hydroxy substituent at the 3-position and a 2-pyridylaminosulphonyl substituent at the 4'-position.

Sulfasalazine: A drug that is used in the management of inflammatory bowel diseases. Its activity is generally considered to lie in its metabolic breakdown product, 5-aminosalicylic acid (see MESALAMINE) released in the colon. (From Martindale, The Extra Pharmacopoeia, 30th ed, p907)
ici 204,219zafirlukast: a leukotriene D4 receptor antagonistcarbamate ester;
indoles;
N-sulfonylcarboxamide
anti-asthmatic agent;
leukotriene antagonist
3,3',5-triiodothyroacetic acidtiratricol : A monocarboxylic acid that is (4-hydroxy-3,5-diiodophenyl)acetic acid in which the phenolic hydroxy group has been replaced by a 4-hydroxy-3-iodophenoxy group. It is a thyroid hormone analogue that has been used in the treatment of thyroid hormone resistance syndrome.
sulfobromophthalein sodiumbromosulfophthalein : An organosulfonic acid that consists of phthalide bearing four bromo substituents at positions 4, 5, 6 and 7 as well as two 4-hydroxy-3-sulfophenyl groups both located at position 1.

bromosulfophthalein sodium : An organic sodium salt that is the disodium salt of bromosulfophthalein.
organic sodium saltdye
taurocholic acidtaurocholate : An organosulfonate oxoanion that is the conjugate base of taurocholic acid.

taurocholic acid : A bile acid taurine conjugate of cholic acid that usually occurs as the sodium salt of bile in mammals.

Taurocholic Acid: The product of conjugation of cholic acid with taurine. Its sodium salt is the chief ingredient of the bile of carnivorous animals. It acts as a detergent to solubilize fats for absorption and is itself absorbed. It is used as a cholagogue and cholerectic.
amino sulfonic acid;
bile acid taurine conjugate
human metabolite
chenodeoxycholic acidchenodeoxycholate : Conjugate base of chenodeoxycholic acid; major species at pH 7.3.

chenodeoxycholic acid : A dihydroxy-5beta-cholanic acid that is (5beta)-cholan-24-oic acid substituted by hydroxy groups at positions 3 and 7 respectively.

Chenodeoxycholic Acid: A bile acid, usually conjugated with either glycine or taurine. It acts as a detergent to solubilize fats for intestinal absorption and is reabsorbed by the small intestine. It is used as cholagogue, a choleretic laxative, and to prevent or dissolve gallstones.
bile acid;
C24-steroid;
dihydroxy-5beta-cholanic acid
human metabolite;
mouse metabolite
glycochenodeoxycholic acidglycochenodeoxycholate : A N-acylglycinate that is the conjugate base of glycochenodeoxycholic acid.

glycochenodeoxycholic acid : A bile acid glycine conjugate having 3alpha,7alpha-dihydroxy-5beta-cholan-24-oyl as the bile acid component.

Glycochenodeoxycholic Acid: A bile salt formed in the liver from chenodeoxycholate and glycine, usually as the sodium salt. It acts as a detergent to solubilize fats for absorption and is itself absorbed. It is a cholagogue and choleretic.
bile acid glycine conjugatehuman metabolite
c.i. direct blue 1
ursodeoxycholic acidursodeoxycholate : A bile acid anion that is the conjugate base of ursodeoxycholic acid, obtained by deprotonation of the carboxy group; major species at pH 7.3.

ursodeoxycholic acid : A bile acid found in the bile of bears (Ursidae) as a conjugate with taurine. Used therapeutically, it prevents the synthesis and absorption of cholesterol and can lead to the dissolution of gallstones.

Ursodeoxycholic Acid: An epimer of chenodeoxycholic acid. It is a mammalian bile acid found first in the bear and is apparently either a precursor or a product of chenodeoxycholate. Its administration changes the composition of bile and may dissolve gallstones. It is used as a cholagogue and choleretic.
bile acid;
C24-steroid;
dihydroxy-5beta-cholanic acid
human metabolite;
mouse metabolite
betulinbetulin : A pentacyclic triterpenoid that is lupane having a double bond at position 20(29) as well as 3beta-hydroxy and 28-hydroxymethyl substituents.

betulin: isolated from various white birch bark (BETULA)
diol;
pentacyclic triterpenoid
analgesic;
anti-inflammatory agent;
antineoplastic agent;
antiviral agent;
metabolite
rosiglitazoneaminopyridine;
thiazolidinediones
EC 6.2.1.3 (long-chain-fatty-acid--CoA ligase) inhibitor;
ferroptosis inhibitor;
insulin-sensitizing drug
bosentan anhydrousBosentan: A sulfonamide and pyrimidine derivative that acts as a dual endothelin receptor antagonist used to manage PULMONARY HYPERTENSION and SYSTEMIC SCLEROSIS.primary alcohol;
pyrimidines;
sulfonamide
antihypertensive agent;
endothelin receptor antagonist
ezetimibeezetimibe : A beta-lactam that is azetidin-2-one which is substituted at 1, 3, and 4 by p-fluorophenyl, 3-(p-fluorophenyl)-3-hydroxypropyl, and 4-hydroxyphenyl groups, respectively (the 3R,3'S,4S enantiomer).

Ezetimibe: An azetidine derivative and ANTICHOLESTEREMIC AGENT that inhibits intestinal STEROL absorption. It is used to reduce total CHOLESTEROL; LDL CHOLESTEROL, and APOLIPOPROTEINS B in the treatment of HYPERLIPIDEMIAS.
azetidines;
beta-lactam;
organofluorine compound
anticholesteremic drug;
antilipemic drug;
antimetabolite
s 8921S 8921: inhibits bile acid transport; structure given in first source
deoxycholic aciddeoxycholic acid : A bile acid that is 5beta-cholan-24-oic acid substituted by hydroxy groups at positions 3 and 12 respectively.

Deoxycholic Acid: A bile acid formed by bacterial action from cholate. It is usually conjugated with glycine or taurine. Deoxycholic acid acts as a detergent to solubilize fats for intestinal absorption, is reabsorbed itself, and is used as a choleretic and detergent.
bile acid;
C24-steroid;
dihydroxy-5beta-cholanic acid
human blood serum metabolite
taurochenodeoxycholic acidtaurochenodeoxycholate : An organosulfonate oxoanion that is the conjugate base of taurochenodeoxycholic acid arising from deprotonation of the sulfonate OH group; major species at pH 7.3.

taurochenodeoxycholic acid : A bile acid taurine conjugate of chenodeoxycholic acid.

Taurochenodeoxycholic Acid: A bile salt formed in the liver by conjugation of chenodeoxycholate with taurine, usually as the sodium salt. It acts as detergent to solubilize fats in the small intestine and is itself absorbed. It is used as a cholagogue and choleretic.
bile acid taurine conjugatehuman metabolite;
mouse metabolite
ritonavirritonavir : An L-valine derivative that is L-valinamide in which alpha-amino group has been acylated by a [(2-isopropyl-1,3-thiazol-4-yl)methyl]methylcarbamoyl group and in which a hydrogen of the carboxamide amino group has been replaced by a (2R,4S,5S)-4-hydroxy-1,6-diphenyl-5-{[(1,3-thiazol-5-ylmethoxy)carbonyl]amino}hexan-2-yl group. A CYP3A inhibitor and antiretroviral drug from the protease inhibitor class used to treat HIV infection and AIDS, it is often used as a fixed-dose combination with another protease inhibitor, lopinavir. Also used in combination with dasabuvir sodium hydrate, ombitasvir and paritaprevir (under the trade name Viekira Pak) for treatment of chronic hepatitis C virus genotype 1 infection as well as cirrhosis of the liver.

Ritonavir: An HIV protease inhibitor that works by interfering with the reproductive cycle of HIV. It also inhibits CYTOCHROME P-450 CYP3A.
1,3-thiazoles;
carbamate ester;
carboxamide;
L-valine derivative;
ureas
antiviral drug;
environmental contaminant;
HIV protease inhibitor;
xenobiotic
(3R,5S)-fluvastatin(3R,5S)-fluvastatin : A (6E)-7-[3-(4-fluorophenyl)-1-(propan-2-yl)-1H-indol-2-yl]-3,5-dihydroxyhept-6-enoic acid diastereoisomer in which the stereocentres beta- and delta- to the carboxy group have R and S configuration, respectively. The drug fluvastatin is an equimolar mixture of this compound and its enantiomer.(6E)-7-[3-(4-fluorophenyl)-1-(propan-2-yl)-1H-indol-2-yl]-3,5-dihydroxyhept-6-enoic acid;
statin (synthetic)
curcumincurcumin : A beta-diketone that is methane in which two of the hydrogens are substituted by feruloyl groups. A natural dyestuff found in the root of Curcuma longa.

Curcumin: A yellow-orange dye obtained from tumeric, the powdered root of CURCUMA longa. It is used in the preparation of curcuma paper and the detection of boron. Curcumin appears to possess a spectrum of pharmacological properties, due primarily to its inhibitory effects on metabolic enzymes.
aromatic ether;
beta-diketone;
diarylheptanoid;
enone;
polyphenol
anti-inflammatory agent;
antifungal agent;
antineoplastic agent;
biological pigment;
contraceptive drug;
dye;
EC 1.1.1.205 (IMP dehydrogenase) inhibitor;
EC 1.1.1.21 (aldehyde reductase) inhibitor;
EC 1.1.1.25 (shikimate dehydrogenase) inhibitor;
EC 1.6.5.2 [NAD(P)H dehydrogenase (quinone)] inhibitor;
EC 1.8.1.9 (thioredoxin reductase) inhibitor;
EC 2.7.10.2 (non-specific protein-tyrosine kinase) inhibitor;
EC 3.5.1.98 (histone deacetylase) inhibitor;
flavouring agent;
food colouring;
geroprotector;
hepatoprotective agent;
immunomodulator;
iron chelator;
ligand;
lipoxygenase inhibitor;
metabolite;
neuroprotective agent;
nutraceutical;
radical scavenger
sodium taurodeoxycholatetaurodeoxycholate : An organosulfonate oxoanion that is the conjugate base of taurodeoxycholic acid.

taurodeoxycholic acid : A bile acid taurine conjugate of deoxycholic acid.

Taurodeoxycholic Acid: A bile salt formed in the liver by conjugation of deoxycholate with taurine, usually as the sodium salt. It is used as a cholagogue and choleretic, also industrially as a fat emulsifier.
bile acid taurine conjugatehuman metabolite
glycodeoxycholic acidglycodeoxycholic acid : A bile acid glycine conjugate of deoxycholic acid.

Glycodeoxycholic Acid: A bile salt formed in the liver by conjugation of deoxycholate with glycine, usually as the sodium salt. It acts as a detergent to solubilize fats for absorption and is itself absorbed. It is used as a cholagogue and choleretic.
bile acid glycine conjugatehuman metabolite
cyclosporineramihyphin A: one of the metabolites produced by Fusarium sp. S-435; RN given refers to cpd with unknown MFhomodetic cyclic peptideanti-asthmatic drug;
anticoronaviral agent;
antifungal agent;
antirheumatic drug;
carcinogenic agent;
dermatologic drug;
EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor;
geroprotector;
immunosuppressive agent;
metabolite
2164u902164U90: a potent inhibitor of the ileal bile acid active transport system; structure given in first source
ursodoxicoltaurinetauroursodeoxycholate : An organosulfonate oxoanion that is the conjugate base of tauroursodeoxycholic acid arising from deprotonation of the sulfonate OH group; major species at pH 7.3.

tauroursodeoxycholic acid : A bile acid taurine conjugate derived from ursoodeoxycholic acid.
bile acid taurine conjugateanti-inflammatory agent;
apoptosis inhibitor;
bone density conservation agent;
cardioprotective agent;
human metabolite;
neuroprotective agent
betulin-3-caffeatebetulin-3-caffeate: has antineoplastic activity; isolated from Hibiscus syriacus; structure in first source
glycoursodeoxycholic acidglycoursodeoxycholate : A N-acylglycinate that is the conjugate base of glycoursodeoxycholic acid. obtained by deprotonation of the carboxy group; major species at pH 7.3.

glycoursodeoxycholic acid : A bile acid glycine conjugate derived from ursoodeoxycholic acid.
bile acid glycine conjugate;
N-acylglycine
human blood serum metabolite;
neuroprotective agent
macitentanaromatic ether;
organobromine compound;
pyrimidines;
ring assembly;
sulfamides
antihypertensive agent;
endothelin receptor antagonist;
orphan drug
tak-875biphenyls