Characterization of an Na(+)-dependent glutamate/aspartate transporter from cultured Bergmann glia.
The properties of a transport system specific for L-glutamate and L-aspartate activity expressed in Bergmann glia cells from chick cerebellum were examined. The uptake of D-[3H]aspartate was inhibited by the endogenous substrates L-aspartate (Ki = 62 microM) and L-glutamate (Ki = 60 microM). Of the identified uptake inhibitors, L-aspartate-beta-hydroxamate (Ki = 900 microM), L-alpha-aminoadipate (Ki = 2000 microM), 4,4'diisothiocyanatos-tilbene-2,2'-disulphonic acid (DIDS) (Ki = 1000 microM) and 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS) (Ki = 100 microM) inhibited D-[3H]aspartate uptake. Northern blot analysis, revealed the expression of a chick homologue of a the rat brain L-glutamate/L-aspartate transporter (GLAST). These data suggest that GLAST may be involved in the regulation of the parallel fibre-Purkinje cell synapse ensheathed by Bergmann glia.
Ruiz
M
M
Departamento de Genética y Biología Molecular, CINVESTAV-IPN, México, DF, México.
Ortega
A
A
D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D027322:Amino Acid Transport System X-AG; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001483:Base Sequence; D002478:Cells, Cultured / Q000502:physiology; D002642:Chick Embryo; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D012964:Sodium / Q000494:pharmacology*
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D001224:Aspartic Acid; D012964:Sodium