Equilibrative nucleoside transporter 1 (ENT1) is a
protein that in humans is encoded by the ''SLC29A1''
gene.
Multiple alternatively spliced variants, encoding the same protein, have been found for this gene.
Expressed on red blood cell surfaces, these variants make up the
Augustine blood group system
The Augustine blood group system is a human blood group system. It includes four red blood cell surface glycoprotein antigens which are encoded by alleles of the gene SLC29A1.
Antigens
The protein which acts as the Augustine antigens is equilibr ...
.
Function
This gene is a member of the equilibrative nucleoside transporter family. The gene encodes a transmembrane
glycoprotein
Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...
that localizes to the plasma and mitochondrial membranes and mediates the cellular uptake of
nucleosides from the surrounding medium. The protein is categorized as an equilibrative (as opposed to concentrative) transporter that is sensitive to inhibition by nitrobenzylmercaptopurine ribonucleoside (NBMPR). Nucleoside transporters are required for nucleotide synthesis in cells that lack ''de novo'' nucleoside synthesis pathways, and are also necessary for the uptake of cytotoxic nucleosides used for cancer and viral chemotherapies.
Genomics
The gene encoding this protein is located on the short arm of
chromosome 6
Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans more than 170 million base pairs (the building material of DNA) and represents between 5.5 and 6% of the total ...
at 6p21.2-p21.1 on the Watson (plus) strand. It is 14,647 bases in length. The encoded protein has 456 amino acid residues with 11 predicted transmembrane domains. The predicted molecular weight is 50.219 kiloDaltons. The protein is post translationally glycosylated and expressed in all tissue with the apparent exception of
skeletal muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
. The highest levels are found in the
liver,
heart,
testis,
spleen,
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
,
kidney and
brain.
Interactive pathway map
Clinical significance
Mutations in this gene have been associated with
H syndrome
H syndrome, also known as Histiocytosis-lymphadenopathy plus syndrome or PHID, is a rare genetic condition caused by mutations in the SLC29A3 gene which encode the human equilibrative nucleoside transporter (hENT3) protein.Moynihan L M, Bundey ...
, pigmented
hypertrichosis with insulin dependent diabetes and
Faisalabad histiocytosis.
Alleles of this gene make up the Augustine blood group system.
Some of the four known variants are highly
immunogenic and
antibodies
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
against them can cause
acute hemolytic transfusion reaction and
hemolytic disease of the fetus and newborn.
See also
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Solute carrier family
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Equilibrative nucleoside transporter
Members of the Equilibrative Nucleoside Transporter (ENT) FamilyTC# 2.A.57 are transport proteins that are specific to nucleosides and nucleobases, and are part of the major facilitator superfamily. They generally possess at least 6, typically 10, ...
s
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Nucleoside transporter
Nucleoside transporters (NTs) are a group of membrane transport proteins which transport nucleoside substrates like adenosine across the membranes of cells and/or vesicles. There are two known types of nucleoside transporters, concentrative nuc ...
s
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Augustine blood group system
The Augustine blood group system is a human blood group system. It includes four red blood cell surface glycoprotein antigens which are encoded by alleles of the gene SLC29A1.
Antigens
The protein which acts as the Augustine antigens is equilibr ...
References
Further reading
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{{Membrane transport proteins
Solute carrier family
Neurotransmitter transporters