Transporters (carrier proteins) are specialized membrane-spanning proteins that assist in the movement of ions, peptides, small molecules, lipids and macromolecules across a biological membrane.
Neurotransmitter Transporters (NT) are a class of transmembrane proteins that carry neurotransmitters across biological membranes to specific cellular and subcellular locations. They are found in the plasma membrane of neurons and glia and many members of this family are sodium-dependent. They often rely on an electrochemical gradient across the membrane to provide energy for neurotransmitter transport, for example Na+ cotransport provides the energy necessary for glutamate transport. NT are found at high concentrations in synaptic clefts where they act to terminate the effects of the neurotransmitter by removing it from the cleft.
Neurotransmitter Transporters are of great clinical interest. They are the pharmacological target of many drugs in the treatment of depression (for example serotonin-noradrenalin reuptake inhibitors (SNRIs)), epilepsy and schizophrenia. In addition, narcotics such as cocaine exert their effects through actions on this class of transporters.