Enzymes
| UniProtKB help_outline | 3 proteins |
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- Name help_outline glycine betaine Identifier CHEBI:17750 (CAS: 107-43-7) help_outline Charge 0 Formula C5H11NO2 InChIKeyhelp_outline KWIUHFFTVRNATP-UHFFFAOYSA-N SMILEShelp_outline C[N+](C)(C)CC([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 21 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline (R)-carnitine Identifier CHEBI:16347 (Beilstein: 4292315,5732837; CAS: 541-15-1) help_outline Charge 0 Formula C7H15NO3 InChIKeyhelp_outline PHIQHXFUZVPYII-ZCFIWIBFSA-N SMILEShelp_outline C[N+](C)(C)C[C@H](O)CC([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 48 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:72119 | RHEA:72120 | RHEA:72121 | RHEA:72122 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
| UniProtKB help_outline |
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Publications
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Functional and pharmacological characterization of human Na(+)-carnitine cotransporter hOCTN2.
Wagner C.A., Luekewille U., Kaltenbach S., Moschen I., Broeer A., Risler T., Broeer S., Lang F.
L-Carnitine is essential for the translocation of acyl-carnitine into the mitochondria for beta-oxidation of long-chain fatty acids. It is taken up into the cells by the recently cloned Na(+)-driven carnitine organic cation transporter OCTN2. Here we expressed hOCTN2 in Xenopus laevis oocytes and ... >> More
L-Carnitine is essential for the translocation of acyl-carnitine into the mitochondria for beta-oxidation of long-chain fatty acids. It is taken up into the cells by the recently cloned Na(+)-driven carnitine organic cation transporter OCTN2. Here we expressed hOCTN2 in Xenopus laevis oocytes and investigated with two-electrode voltage-clamp and flux measurements its functional and pharmacological properties as a Na(+)-carnitine cotransporter. L-carnitine transport was electrogenic. The L-carnitine-induced currents were voltage and Na(+) dependent, with half-maximal currents at 0.3 +/-0.1 mM Na(+) at -60 mV. Furthermore, L-carnitine-induced currents were pH dependent, decreasing with acidification. In contrast to other members of the organic cation transporter family, hOCTN2 functions as a Na(+)-coupled carnitine transporter. Carnitine transport was stereoselective, with an apparent Michaelis-Menten constant (K(m)) of 4.8 +/-0.3 microM for L-carnitine and 98.3 +/-38.0 microM for D-carnitine. The substrate specificity of hOCTN2 differs from rOCT-1 and hOCT-2 as hOCTN2 showed only small currents with classic OCT substrates such as choline or tetraethylammonium; by contrast hOCTN2 mediated transport of betaine. hOCTN2 was inhibited by several drugs known to induce secondary carnitine deficiency. Most potent blockers were the antibiotic emetine and the ion channel blockers quinidine and verapamil. The apparent IC(50) for emetine was 4.2 +/-1.2 microM. The anticonvulsant valproic acid did not induce a significant inhibition of carnitine transport, pointing to a different mode of action. In summary, hOCTN2 mediates electrogenic Na(+)-dependent stereoselective high-affinity transport of L-carnitine and Na(+). hOCTN2 displays transport properties distinct from other members of the OCT family and is directly inhibited by several substances known to induce systemic carnitine deficiency. << Less
Am. J. Physiol. 279:F584-F591(2000) [PubMed] [EuropePMC]
This publication is cited by 3 other entries.