BROWSE

Related Researcher

Author

Kwon, H. Moo
Inflammation and Kidney Disorder Lab
Research Interests
  • TonEBP, Obesity, Cancer, Chronic inflammatory diseases, Brain disorder, Kidney disorders, Genomic instability

ITEM VIEW & DOWNLOAD

Functional characterization of the betaine/gamma-aminobutyric acid transporter BGT-1 expressed in Xenopus oocytes

Cited 47 times inthomson ciCited 46 times inthomson ci
Title
Functional characterization of the betaine/gamma-aminobutyric acid transporter BGT-1 expressed in Xenopus oocytes
Author
Matskevitch, IWagner, CAStegen, CBroer, SNoll, BRisler, TKwon, HMHandler, JSWaldegger, SBusch, AELang, F
Keywords
VOLUME REGULATORY MECHANISMS; BRAIN GABA TRANSPORTER; RAT-BRAIN; MOLECULAR-CLONING; MOUSE-BRAIN; CDNA; HETEROGENEITY; CHANNELS; CELLS
Issue Date
199906
Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Citation
JOURNAL OF BIOLOGICAL CHEMISTRY, v.274, no.24, pp.16709 - 16716
Abstract
Betaine is an osmolyte accumulated in cells during osmotic cell shrinkage. The canine transporter mediating cellular accumulation of the osmolyte betaine and the neurotransmitter γ-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 γ- 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 = β-alanine > proline = quinidine > dimethylglycine > glycine > sarcosine. Both the V(max) and K(m) 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 K(m) 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.
URI
Go to Link
DOI
http://dx.doi.org/10.1074/jbc.274.24.16709
ISSN
0021-9258
Appears in Collections:
SLS_Journal Papers

find_unist can give you direct access to the published full text of this article. (UNISTARs only)

Show full item record

qr_code

  • mendeley

    citeulike

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

MENU