ATP-binding cassette sub-family G member 8
Domain
A functional Walker motif (consensus sequence G-X-X-G-X-G-K-[ST]-T) is expected to bind ATP. The essential Lys in this region is not conserved in ABCG8 (G-S-S-G-C-R-A-S) and is not required for transport activity mediated by the heterodimer with ABCG5.
Function
ABCG5 and ABCG8 form an obligate heterodimer that mediates Mg(2+)- and ATP-dependent sterol transport across the cell membrane. Plays an essential role in the selective transport of the dietary cholesterol in and out of the enterocytes and in the selective sterol excretion by the liver into bile (PubMed:11099417, PubMed:11452359, PubMed:15054092, PubMed:27144356). Required for normal sterol homeostasis (PubMed:11099417, PubMed:11452359, PubMed:15054092). The heterodimer with ABCG5 has ATPase activity (PubMed:16893193, PubMed:20210363, PubMed:27144356).
Involvement in disease
Gallbladder disease 4
GBD4
One of the major digestive diseases. Gallstones composed of cholesterol (cholelithiasis) are the common manifestations in western countries. Most people with gallstones, however, remain asymptomatic through their lifetimes.
None
Disease susceptibility may be associated with variants affecting the gene represented in this entry.
Sitosterolemia 1
STSL1
A form of sitosterolemia, an autosomal recessive metabolic disorder characterized by unregulated intestinal absorption of cholesterol, phytosterols and shellfish sterols, and decreased biliary excretion of dietary sterols into bile. Patients have hypercholesterolemia, very high levels of plant sterols in the plasma, and frequently develop tendon and tuberous xanthomas, accelerated atherosclerosis and premature coronary artery disease.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
N-glycosylated.
Sequence Similarities
Belongs to the ABC transporter superfamily. ABCG family. Eye pigment precursor importer (TC 3.A.1.204) subfamily.
Tissue Specificity
Predominantly expressed in the liver (PubMed:11099417, PubMed:11452359). Low expression levels in the small intestine and colon (PubMed:11099417). Very low levels in other tissues, including brain, heart and spleen (PubMed:11452359).
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- Apical cell membrane
- Multi-pass membrane protein
Alternative names
ATP-binding cassette sub-family G member 8, Sterolin-2, ABCG8