Enzymes
| UniProtKB help_outline | 266 proteins |
Reaction participants Show >> << Hide
- Name help_outline 4-aminobutanoate Identifier CHEBI:59888 Charge 0 Formula C4H9NO2 InChIKeyhelp_outline BTCSSZJGUNDROE-UHFFFAOYSA-N SMILEShelp_outline [NH3+]CCCC([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 23 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline chloride Identifier CHEBI:17996 (Beilstein: 3587171; CAS: 16887-00-6) help_outline Charge -1 Formula Cl InChIKeyhelp_outline VEXZGXHMUGYJMC-UHFFFAOYSA-M SMILEShelp_outline [Cl-] 2D coordinates Mol file for the small molecule Search links Involved in 139 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline Na+ Identifier CHEBI:29101 (CAS: 17341-25-2) help_outline Charge 1 Formula Na InChIKeyhelp_outline FKNQFGJONOIPTF-UHFFFAOYSA-N SMILEShelp_outline [Na+] 2D coordinates Mol file for the small molecule Search links Involved in 254 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:70731 | RHEA:70732 | RHEA:70733 | RHEA:70734 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Functional characterization of the Betaine/gamma-aminobutyric acid transporter BGT-1 expressed in Xenopus oocytes.
Matskevitch I., Wagner C.A., Stegen C., Broeer S., Noll B., Risler T., Kwon H.M., Handler J.S., Waldegger S., Busch A.E., Lang F.
Betaine is an osmolyte accumulated in cells during osmotic cell shrinkage. The canine transporter mediating cellular accumulation of the osmolyte betaine and the neurotransmitter gamma-aminobutyric acid (BGT-1) was expressed in Xenopus oocytes and analyzed by two-electrode voltage clamp and tracer ... >> More
Betaine is an osmolyte accumulated in cells during osmotic cell shrinkage. The canine transporter mediating cellular accumulation of the osmolyte betaine and the neurotransmitter gamma-aminobutyric acid (BGT-1) was expressed in Xenopus oocytes and analyzed by two-electrode voltage clamp and tracer flux studies. Exposure of oocytes expressing BGT-1 to betaine or gamma-aminobutyric acid (GABA) depolarized the cell membrane in the current clamp mode and induced an inward current under voltage clamp conditions. At 1 mM substrate the induced currents decreased in the following order: betaine = GABA > diaminobutyric acid = beta-alanine > proline = quinidine > dimethylglycine > glycine > sarcosine. Both the Vmax and Km of GABA- and betaine-induced currents were voltage-dependent, and GABA- and betaine-induced currents and radioactive tracer uptake were strictly Na+-dependent but only partially dependent on the presence of Cl-. The apparent affinity of GABA decreased with decreasing Na+ concentrations. The Km of Na+ also depended on the GABA and Cl- concentration. A decrease of the Cl-concentration reduced the apparent affinity for Na+ and GABA, and a decrease of the Na+ concentration reduced the apparent affinity for Cl- and GABA. A comparison of 22Na+-, 36Cl--, and 14C-labeled GABA and 14C-labeled betaine fluxes and GABA- and betaine-induced currents yielded a coupling ratio of Na+/Cl-/organic substrate of 3:1:1 or 3:2:1. Based on the data, a transport model of ordered binding is proposed in which GABA binds first, Na+ second, and Cl-third. In conclusion, BGT-1 displays significant functional differences from the other members of the GABA transporter family. << Less
J. Biol. Chem. 274:16709-16716(1999) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.