Biomaterial Database

Serine-O-sulphate transport by the human glutamate transporter, EAAT2. 1998

R J Vandenberg, and A D Mitrovic, and G A Johnston

Department of Pharmacology, University of Sydney, NSW, Australia.

1. Expression of the recombinant human excitatory amino aid transporters, EAAT1 and EAAT2, in Xenopus laevis oocytes allows electrogenic transport to be studied under voltage clamp conditions. 2. We have investigated the transport of the pharmacological substrate, L-serine-O-sulphate transport by EAAT1 and EAAT2. The EC50 values for L-serine-O-sulphate transport by EAAT2 showed a steep voltage-dependence, increasing from 152+/-11 microM at - 100 mV to 1930+/-160 microM at 0 mV. In contrast to EAAT2, EC50 values for L-serine-O-sulphate transport by EAAT1 were relatively constant over the membrane potential range of - 100 mV to 0 mV. The EC50 values for L-glutamate and D-aspartate transport, by EAAT2, were also relatively constant over this membrane potential range. 3. Chloride ions modulated the voltage-dependent changes in EC50 values for transport by EAAT2. This effect was most apparent for L-serine-O-sulphate transport, and to a lesser extent for L-glutamate and not at all for D-aspartate transport by EAAT2. 4. Extracellular sodium and proton concentrations also modulated the voltage-dependence of L-serine-O-sulphate EC50 values for EAAT2. 5. We speculate that these different properties of L-serine-O-sulphate transport by EAAT2 compared to other substrates may be due to the much stronger acidity of the sulphate group of L-serine-O-sulphate compared to carboxyl groups of L-glutamate or D-aspartate. 6. These results highlight some of the differences in the way different glutamate transporter subtypes transport substrates. This may be used to understand further the transport process and develop subtype selective inhibitors of glutamate transport.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012694	Serine	A non-essential amino acid occurring in natural form as the L-isomer. It is synthesized from GLYCINE or THREONINE. It is involved in the biosynthesis of PURINES; PYRIMIDINES; and other amino acids.	L-Serine,L Serine