L-Glutamate transporter derived from mRNAs of primary glial cultures: expression in Xenopus laevis oocytes

Abstract

A high-affinity sodium-dependent l-glutamate transporter was expressed in Xenopus oocytes after microinjection of poly(A) + RNA from primary astrocyte cultures from rat brain cortex. mRNA-induced l-glutamate transport was saturable by substrate and shows kinetic features similar to those found in intact glial cell preparations. l-Glutamate accumulation was prevented by rising the external K + concentration or by coincubation with l-, d-aspartate or d-glutamate. After fractionation by sucrose density gradient, the mRNA encoding for the expressed l-glutamate transporter from glial cells was found in fractions containing messages of 2.05–2.9 kilobases (kb) in length.