background:
The heteromeric transporter OST Alpha/OST Beta facilitates the transport of bile and other steroid solutes across the basolateral epithelial cell membrane of intestine, liver, testis, kidney and adrenal gland. OST Alpha/OST Beta expression is induced by bile acids through ligand-dependent transactivation of their genes by FXR (Farnesoid X-activated receptor). This genetic regulation suggests that in response to changes in intracellular bile acid levels, bile acids adjust the rate of their own efflux from enterocytes. OST Beta is a 128 amino acid single-pass transmembrane protein that requires OST Alpha to localize to the plasma membrane. Coexpression of OST Alpha and OST Beta is also required to convert the OST Alpha subunit to a mature glycosylated endoglycosidase H-resistant form, suggesting that co-expression facilitates trafficking of OST Alpha through the golgi apparatus. Though widely expressed, OST Beta is present at highest levels in ileum.
Function:
Essential component of the Ost-alpha/Ost-beta complex, a heterodimer that acts as the intestinal basolateral transporter responsible for bile acid export from enterocytes into portal blood. Efficiently transports the major species of bile acids. Modulates SLC51A glycosylation, membrane trafficking and stability activities.
Subunit:
Interacts with SLC51A. The Ost-alpha/Ost-beta complex is a heterodimer composed of alpha (SLC51A) and beta (SLC51B) subunit; induces the transport of SLC51A from the reticulum endoplasmic to the plasma membrane.
Subcellular Location:
Cell membrane. Mainly restricted to the lateral and basal membranes of ileal enterocytes.
Tissue Specificity:
Widely expressed with a high expression in ileum. Expressed in testis, colon, liver, small intestine, kidney, ovary and adrenal gland; and at low levels in heart, lung, brain, pituitary, thyroid gland, uterus, prostate, mammary gland and fat.
Similarity:
Belongs to the OST-beta family.
Database links:
UniProtKB/Swiss-Prot: Q86UW2.2
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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