Transport direction determines the kinetics of substrate transport by the glutamate transporter EAAC1.

ABSTRACT: Glutamate transport by the excitatory amino acid carrier EAAC1 is known to be reversible. Thus, glutamate can either be taken up into cells, or it can be released from cells through reverse transport, depending on the electrochemical gradient of the co- and countertransported ions. However, it is unknown how fast and by which reverse transport mechanism glutamate can be released from cells. Here, we determined the steady- and pre-steady-state kinetics of reverse glutamate transport with submillisecond time resolution. First, our results suggest that glutamate and Na(+) dissociate from their cytoplasmic binding sites sequentially, with glutamate dissociating first, followed by the three cotransported Na(+) ions. Second, the kinetics of glutamate transport depend strongly on transport direct

SUBMITTER: Zhang Z 

PROVIDER: S-EPMC2084290 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature