Excitatory amino acid transporter

Excitatory Amino Acid Transporter (EAAT) is a type of membrane transport protein that is primarily responsible for the reuptake of glutamate and aspartate in the central nervous system. These transporters play a crucial role in maintaining the extracellular concentration of glutamate within the physiological range, thereby preventing excitotoxicity.

Function

EAATs are responsible for the termination of neurotransmission at synaptic clefts. They achieve this by rapidly removing released glutamate and aspartate, which are excitatory amino acids, from the extracellular space, thereby preventing overstimulation of the post-synaptic neuron.

Types

There are five known types of EAATs in mammals, namely EAAT1, EAAT2, EAAT3, EAAT4, and EAAT5. Each type has a different distribution within the brain and other parts of the body, and they also vary in their transport kinetics and voltage dependence.

EAAT1

EAAT1, also known as GLAST (glutamate/aspartate transporter), is predominantly expressed in the cerebellum, forebrain, and spinal cord. It is primarily found in astrocytes, a type of glial cell.

EAAT2

EAAT2, also known as GLT-1 (glutamate transporter 1), is the most abundant EAAT in the brain. It is primarily found in astrocytes, but it is also present in neurons.

EAAT3

EAAT3, also known as EAAC1 (excitatory amino acid carrier 1), is widely distributed throughout the brain and is primarily found in neurons.

EAAT4

EAAT4 is predominantly expressed in the cerebellum, specifically in Purkinje cells, a type of neuron.

EAAT5

EAAT5 is primarily found in the retina, where it is thought to play a role in visual signal processing.

Clinical Significance

Alterations in EAAT function have been implicated in a number of neurological and psychiatric disorders, including epilepsy, Alzheimer's disease, schizophrenia, and depression. Therefore, EAATs are considered potential therapeutic targets for these conditions.