Glutamate aspartate transporter
Encyclopedia
Solute carrier family 1 (glial high-affinity glutamate transporter), member 3, also known as SLC1A3,is a protein
that, in humans, is encoded by the SLC1A3 gene
. SLC1A3 is also often called the GLutamate ASpartate Transporter (GLAST) or Excitatory Amino Acid Transporter 1 (EAAT1) .
GLAST is a protein in the inner mitochondrial membrane
that is part of the malate-aspartate shuttle
.
and aspartic acid
with the cotransport
of three Na+
and one H+
cations
and counter transport of one K+
cation. This co-transport coupling (or symport) allows the transport of glutamate into cells against a concentration gradient.
s and Bergmann glia in the cerebellum
. In the retina, GLAST is expressed in Muller cells. GLAST is also expressed in a number of other tissues including cardiac myocytes.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that, in humans, is encoded by the SLC1A3 gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
. SLC1A3 is also often called the GLutamate ASpartate Transporter (GLAST) or Excitatory Amino Acid Transporter 1 (EAAT1) .
GLAST is a protein in the inner mitochondrial membrane
Inner mitochondrial membrane
The mitochondrial inner membrane forms internal compartments known as cristae, which allow greater space for the proteins such as cytochromes to function properly and efficiently. The electron transport chain is located on the inner membrane of the mitochondria...
that is part of the malate-aspartate shuttle
Malate-aspartate shuttle
The malate-aspartate shuttle is a biochemical system for translocating electrons produced during glycolysis across the semipermeable inner membrane of the mitochondrion for oxidative phosphorylation in eukaryotes. These electrons enter the electron transport chain of the mitochondria via reduction...
.
Mechanism
GLAST mediates the transport of glutamicGlutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
and aspartic acid
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
with the cotransport
Co-transport
Co-transport, also known as coupled transport or secondary active transport, refers to the simultaneous or sequential passive transfer of molecules or ions across biological membranes in a fixed ratio...
of three Na+
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
and one H+
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
cations
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
and counter transport of one K+
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
cation. This co-transport coupling (or symport) allows the transport of glutamate into cells against a concentration gradient.
Tissue distribution
GLAST is highly expressed in astrocyteAstrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...
s and Bergmann glia in the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
. In the retina, GLAST is expressed in Muller cells. GLAST is also expressed in a number of other tissues including cardiac myocytes.