Page last updated: 2024-10-24
cobalamin transport
Definition
Target type: biologicalprocess
The directed movement of cobalamin (vitamin B12), a water-soluble vitamin characterized by possession of a corrin nucleus containing a cobalt atom, into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. [GOC:ai]
Cobalamin (vitamin B12) transport is a complex process involving multiple steps and proteins. It begins with the uptake of cobalamin from the diet, primarily from animal products.
1. **Dietary Cobalamin Binding:** Cobalamin binds to **R-binders**, proteins secreted by salivary glands and gastric juice, in the stomach. This binding protects cobalamin from degradation by gastric enzymes.
2. **Gastric Digestion and Release:** In the acidic environment of the stomach, R-binders release cobalamin, which then binds to **intrinsic factor (IF)**, a glycoprotein produced by parietal cells in the stomach. This IF-cobalamin complex is resistant to digestion in the small intestine.
3. **Small Intestine Absorption:** The IF-cobalamin complex travels to the ileum, the last segment of the small intestine. Here, the complex binds to **cubilin**, a receptor protein on the surface of ileal enterocytes. The complex is then internalized by endocytosis.
4. **Intracellular Trafficking:** Once inside the enterocyte, cobalamin detaches from IF. It then binds to **transcobalamin II (TCII)**, a transport protein that is responsible for delivering cobalamin to the bloodstream.
5. **Bloodstream Transport:** TCII-cobalamin complex enters the bloodstream. This complex circulates throughout the body, delivering cobalamin to various cells and tissues.
6. **Cellular Uptake:** Cells take up cobalamin from the bloodstream through receptor-mediated endocytosis. The receptor that binds to TCII is called **cubam**, which is expressed on the cell surface.
7. **Cellular Metabolism:** Inside cells, cobalamin is required for the activity of two key enzymes: **methylmalonyl-CoA mutase** and **methionine synthase**. These enzymes play crucial roles in the metabolism of carbohydrates, fatty acids, and amino acids.
Cobalamin transport is essential for normal cell growth, development, and function. Deficiencies in cobalamin can lead to various health problems, including megaloblastic anemia, neurological disorders, and congenital malformations.'
"
Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Multidrug resistance-associated protein 1 | A multidrug resistance-associated protein 1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P33527] | Homo sapiens (human) |
| Multidrug resistance-associated protein 1 | A multidrug resistance-associated protein 1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P33527] | Homo sapiens (human) |
Compounds (54)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| 4-phenyl-3-furoxancarbonitrile | 4-phenyl-3-furoxancarbonitrile : A 1,2,5-oxadiazole substituted by an oxido, cyano and phenyl groups at positions 2, 3 and 4, respectively. It is a vasodilator and inhibitor of platelet aggregation. 4-phenyl-3-furoxancarbonitrile: structure given in first source | 1,2,5-oxadiazole; benzenes; N-oxide; nitrile | geroprotector; nitric oxide donor; platelet aggregation inhibitor; soluble guanylate cyclase activator; vasodilator agent |
| p-aminohippuric acid | p-aminohippurate : A hippurate that is the conjugate base of p-aminohippuric acid, arising from deprotonation of the carboxy group. p-aminohippuric acid : An N-acylglycine that is the 4-amino derivative of hippuric acid; used as a diagnostic agent in the measurement of renal plasma flow. p-Aminohippuric Acid: The glycine amide of 4-aminobenzoic acid. Its sodium salt is used as a diagnostic aid to measure effective renal plasma flow (ERPF) and excretory capacity. | N-acylglycine | Daphnia magna metabolite |
| benzbromarone | benzbromarone : 1-Benzofuran substituted at C-2 and C-3 by an ethyl group and a 3,5-dibromo-4-hydroxybenzoyl group respectively. An inhibitor of CYP2C9, it is used as an anti-gout medication. Benzbromarone: Uricosuric that acts by increasing uric acid clearance. It is used in the treatment of gout. | 1-benzofurans; aromatic ketone | uricosuric drug |
| verapamil | 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile : A tertiary amino compound that is 3,4-dimethoxyphenylethylamine in which the hydrogens attached to the nitrogen are replaced by a methyl group and a 4-cyano-4-(3,4-dimethoxyphenyl)-5-methylhexyl group. verapamil : A racemate comprising equimolar amounts of dexverapamil and (S)-verapamil. An L-type calcium channel blocker of the phenylalkylamine class, it is used (particularly as the hydrochloride salt) in the treatment of hypertension, angina pectoris and cardiac arrhythmia, and as a preventive medication for migraine. Verapamil: A calcium channel blocker that is a class IV anti-arrhythmia agent. | aromatic ether; nitrile; polyether; tertiary amino compound | |
| indomethacin | indometacin : A member of the class of indole-3-acetic acids that is indole-3-acetic acid in which the indole ring is substituted at positions 1, 2 and 5 by p-chlorobenzoyl, methyl, and methoxy groups, respectively. A non-steroidal anti-inflammatory drug, it is used in the treatment of musculoskeletal and joint disorders including osteoarthritis, rheumatoid arthritis, gout, bursitis and tendinitis. Indomethacin: A non-steroidal anti-inflammatory agent (NSAID) that inhibits CYCLOOXYGENASE, which is necessary for the formation of PROSTAGLANDINS and other AUTACOIDS. It also inhibits the motility of POLYMORPHONUCLEAR LEUKOCYTES. | aromatic ether; indole-3-acetic acids; monochlorobenzenes; N-acylindole | analgesic; drug metabolite; EC 1.14.99.1 (prostaglandin-endoperoxide synthase) inhibitor; environmental contaminant; gout suppressant; non-steroidal anti-inflammatory drug; xenobiotic; xenobiotic metabolite |
| mitoxantrone | mitoxantrone : A dihydroxyanthraquinone that is 1,4-dihydroxy-9,10-anthraquinone which is substituted by 6-hydroxy-1,4-diazahexyl groups at positions 5 and 8. Mitoxantrone: An anthracenedione-derived antineoplastic agent. | dihydroxyanthraquinone | analgesic; antineoplastic agent |
| vincristine | acetate ester; formamides; methyl ester; organic heteropentacyclic compound; organic heterotetracyclic compound; tertiary alcohol; tertiary amino compound; vinca alkaloid | antineoplastic agent; drug; microtubule-destabilising agent; plant metabolite; tubulin modulator | |
| alpha-naphthoflavone | alpha-naphthoflavone : An extended flavonoid resulting from the formal fusion of a benzene ring with the h side of flavone. A synthetic compound, it is an inhibitor of aromatase (EC 1.14.14.14). alpha-naphthoflavone: inhibits P4501A1 and P4501A2; stimulates some activities of P4503A4 | extended flavonoid; naphtho-gamma-pyrone; organic heterotricyclic compound | aryl hydrocarbon receptor agonist; aryl hydrocarbon receptor antagonist; EC 1.14.14.14 (aromatase) inhibitor |
| dehydroepiandrosterone sulfate | dehydroepiandrosterone sulfate : A steroid sulfate that is the 3-sulfooxy derivative of dehydroepiandrosterone. Dehydroepiandrosterone Sulfate: The circulating form of a major C19 steroid produced primarily by the ADRENAL CORTEX. DHEA sulfate serves as a precursor for TESTOSTERONE; ANDROSTENEDIONE; ESTRADIOL; and ESTRONE. | 17-oxo steroid; steroid sulfate | EC 2.7.1.33 (pantothenate kinase) inhibitor; human metabolite; mouse metabolite |
| vinblastine | |||
| daunorubicin | anthracycline : Anthracyclines are polyketides that have a tetrahydronaphthacenedione ring structure attached by a glycosidic linkage to the amino sugar daunosamine. daunorubicin : A natural product found in Actinomadura roseola. Daunorubicin: A very toxic anthracycline aminoglycoside antineoplastic isolated from Streptomyces peucetius and others, used in treatment of LEUKEMIA and other NEOPLASMS. | aminoglycoside antibiotic; anthracycline; p-quinones; tetracenequinones | antineoplastic agent; bacterial metabolite |
| cefadroxil anhydrous | cefadroxil : A cephalosporin bearing methyl and (2R)-2-amino-2-(4-hydroxyphenyl)acetamido groups at positions 3 and 7, respectively, of the cephem skeleton. Cefadroxil: Long-acting, broad-spectrum, water-soluble, CEPHALEXIN derivative. | cephalosporin | antibacterial drug |
| fluorexon | fluorexon: structure | xanthene dye | fluorochrome |
| glutathione disulfide | Glutathione Disulfide: A GLUTATHIONE dimer formed by a disulfide bond between the cysteine sulfhydryl side chains during the course of being oxidized. | glutathione derivative; organic disulfide | Escherichia coli metabolite; mouse metabolite |
| dexverapamil | dexverapamil : A 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile that has R configuration. It competitively inhibits the multidrug resistance efflux pump P-glycoprotein (MDR-1, EC 3.6.3.44), thereby potentially increasing the effectiveness of a wide range of antineoplastic drugs which are inactivated by MDR-1 mechanisms. Dexverapamil exhibits lower calcium antagonistic activity and toxicity than racemic verapamil. | 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile | EC 3.6.3.44 (xenobiotic-transporting ATPase) inhibitor |
| estradiol-3-sulfate | 17beta-estradiol 3-sulfate : A steroid sulfate obtained by the formal condensation of sulfuric acid with the 3-hydroxy group of 17beta-estradiol. estradiol-3-sulfate: RN given refers to (17beta)-isomer | 17beta-hydroxy steroid; steroid sulfate | mammalian metabolite |
| sulfolithocholylglycine | sulfoglycolithocholic acid : The 3-O-sulfo derivative of glycolithocholic acid. | bile acid glycine conjugate; steroid sulfate | |
| hernandezine | hernandezine: from Thalictrum glandulosissimum; structure given in first source; RN given refers to (1beta)-isomer; RN for cpd without isomeric designation not avail 3/91 | bisbenzylisoquinoline alkaloid; isoquinolines | |
| lekoptin | (S)-verapamil : A 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile that has S configuration. | 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile | |
| 3,5,7,3',4'-pentamethoxyflavone | 3,5,7,3',4'-pentamethoxyflavone: causes relaxation of cavernosum; structure in first source | ||
| sr141716 | amidopiperidine; carbohydrazide; dichlorobenzene; monochlorobenzenes; pyrazoles | anti-obesity agent; appetite depressant; CB1 receptor antagonist | |
| fluo-3 | Fluo-3: fluorescent Ca(2+) indicator; permits continuous monitoring of Ca without interference with use of UV-sensitive caged compounds | xanthene dye | fluorochrome |
| elacridar | Elacridar: inhibitor of MDR1 PROTEIN; structure given in first source | ||
| methotrexate | dicarboxylic acid; monocarboxylic acid amide; pteridines | abortifacient; antimetabolite; antineoplastic agent; antirheumatic drug; dermatologic drug; DNA synthesis inhibitor; EC 1.5.1.3 (dihydrofolate reductase) inhibitor; immunosuppressive agent | |
| tariquidar | benzamides | ||
| 4-methyl-3-(phenylsulfonyl)furoxan | 4-methyl-3-(phenylsulfonyl)furoxan: structure given in first source; a human guanylate cyclase activator | ||
| etravirine | aminopyrimidine; aromatic ether; dinitrile; organobromine compound | antiviral agent; HIV-1 reverse transcriptase inhibitor | |
| 3',4'-dimethoxy-alpha-naphthoflavone | 3',4'-dimethoxy-alpha-naphthoflavone: activated Ah receptor; structure in first source | ||
| naringenin | (S)-naringenin : The (S)-enantiomer of naringenin. | (2S)-flavan-4-one; naringenin | expectorant; plant metabolite |
| reversan | reversan: inhibits multidrug resistance-associated protein 1 | ||
| estrone sulfate | estrone sulfate: sulfoconjugated estrone; RN given refers to parent cpd | 17-oxo steroid; steroid sulfate | human metabolite; mouse metabolite |
| biricodar | biricodar: a non-macrocyclic ligand for FKBP12; structure in first source | alpha-amino acid ester | |
| quercetin | 7-hydroxyflavonol; pentahydroxyflavone | antibacterial agent; antineoplastic agent; antioxidant; Aurora kinase inhibitor; chelator; EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor; geroprotector; phytoestrogen; plant metabolite; protein kinase inhibitor; radical scavenger | |
| apigenin | Chamomile: Common name for several daisy-like plants (MATRICARIA; TRIPLEUROSPERMUM; ANTHEMIS; CHAMAEMELUM) native to Europe and Western Asia, now naturalized in the United States and Australia. | trihydroxyflavone | antineoplastic agent; metabolite |
| chrysoeriol | 4',5,7-trihydroxy-3'-methoxyflavone : The 3'-O-methyl derivative of luteolin. chrysoeriol: isolated from leaves of Eurya japonica & E. emarginata | monomethoxyflavone; trihydroxyflavone | antineoplastic agent; antioxidant; metabolite |
| ayanin | 3',5-dihydroxy-3,4',7-trimethoxyflavone : A trimethoxyflavone that is quercetin in which the hydroxy groups at positions 3, 4' and 7 have been replaced by methoxy groups. ayanin: has cytoprotective and anti-neuroinflammatory activities; isolated from Croton schiedeanus (Euphorbiaceae); structure in first source | dihydroxyflavone; trimethoxyflavone | plant metabolite |
| kaempferol | 7-hydroxyflavonol; flavonols; tetrahydroxyflavone | antibacterial agent; geroprotector; human blood serum metabolite; human urinary metabolite; human xenobiotic metabolite; plant metabolite | |
| diosmetin | 3'-hydroxyflavonoid; monomethoxyflavone; trihydroxyflavone | angiogenesis inhibitor; anti-inflammatory agent; antineoplastic agent; antioxidant; apoptosis inducer; bone density conservation agent; cardioprotective agent; plant metabolite; tropomyosin-related kinase B receptor agonist; vasodilator agent | |
| myricetin | 7-hydroxyflavonol; hexahydroxyflavone | antineoplastic agent; antioxidant; cyclooxygenase 1 inhibitor; food component; geroprotector; hypoglycemic agent; plant metabolite | |
| robinetin | robinetin : A pentahydroxyflavone that is flavone substituted by hydroxy groups at positions 3, 7, 3, 4' and 5'. robinetin: structure given in first source | 7-hydroxyflavonol; pentahydroxyflavone | plant metabolite |
| sdz psc 833 | valspodar: nonimmunosuppressive cyclosporin analog which is a potent multidrug resistance modifier; 7-10 fold more potent than cyclosporin A; a potent P glycoprotein inhibitor; MW 1215 | homodetic cyclic peptide | |
| estradiol-17 beta-glucuronide | 17beta-estradiol 17-glucosiduronic acid : A steroid glucosiduronic acid that consists of 17beta-estradiol having a beta-glucuronyl residue attached at position 17 via a glycosidic linkage. | 3-hydroxy steroid; steroid glucosiduronic acid | |
| l 660,711 | quinolines | ||
| cyclosporine | ramihyphin A: one of the metabolites produced by Fusarium sp. S-435; RN given refers to cpd with unknown MF | homodetic cyclic peptide | anti-asthmatic drug; anticoronaviral agent; antifungal agent; antirheumatic drug; carcinogenic agent; dermatologic drug; EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor; geroprotector; immunosuppressive agent; metabolite |
| licochalcone a | licochalcone A: has both anti-inflammatory and antineoplastic activities; structure given in first source; isolated from root of Glycyrrhiza inflata; RN given refers to (E)-isomer | chalcones | |
| 5-hydroxy-3,3',4',7-tetramethoxyflavone | 5-hydroxy-3,3',4',7-tetramethoxyflavone : A monohydroxyflavone that is 5-hydroxyflavone which is substituted by methoxy groups at positions 3,3',4' and 7. 5-hydroxy-3,7,3',4'-tetramethoxyflavone: from the rhizome of Kaempferia parviflora; inhibits monocyte adhesion and cellular reactive oxygen species production in human umbilical vein endothelial cells | 3'-methoxyflavones; monohydroxyflavone; tetramethoxyflavone | plant metabolite |
| 2,3-dehydrosilybin | dehydrosilybin: inhibits cytochrome P450 1A1 catalytic activity; structure in first source | flavonolignan | |
| verlukast | verlukast: LTD4 receptor antagonist | ||
| 4-ethoxy-3-phenylsulfonylfuroxan | |||
| ko 143 | beta-carbolines; tert-butyl ester | ||
| wk-x-34 | WK-X-34: inhibitor of P-glycoprotein and BCRP (breast cancer resistance protein); structure in first source | ||
| mk 0571 | |||
| bms 754807 | BMS 754807: an IGR-1R kinase inhibitor; structure in first source | pyrazoles; pyridines; pyrrolidines; pyrrolotriazine | antineoplastic agent; EC 2.7.10.1 (receptor protein-tyrosine kinase) inhibitor |
| gs-9451 |