Neuronal and glial glutamate transporters remove the excitatory neurotransmitter glutamate from the synaptic cleft and thus prevent neurotoxicity, The proteins belong to a large family of secondary transporters, which includes transporters from a variety of bacterial, archaeal and eukaryotic organisms. The transporters consist of eight membrane-spanning alpha -helices and two pore-loop structures, which are unique among secondary transporters but may resemble pore-loops found in ion channels, Another distinctive structural feature is the presence of a highly amphipathic membrane-spanning alpha -helix that provides a hydrophilic path through the membrane. The unusual structural features of the transporters are discussed in relation to their function. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.