Organic Solute Transporter Beta (OSTb)

OST-beta together with OST-alpha is able to transport estrone sulfate, taurocholate, digoxin, and prostaglandin E2 across cell membranes. The Ost-alpha / Ost-beta heterodimer, but not the individual subunits, stimulates sodium-independent bile acid uptake. The heterodimer furthermore is essential for intestinal bile acid transport.
OST-alpha and OST-alpha have high expression in the testis, colon, liver, small intestine, kidney, ovary, and adrenal gland.The deduced mouse and human OST-beta proteins contain 128 amino acids and share 63% amino acid identity. Real-time PCR showed high levels of both OST-alpha and OST-beta in human testis, colon, liver, small intestine, kidney, ovary, and adrenal gland, with lower levels in heart, lung, brain, pituitary, thyroid gland, uterus, prostate, mammary gland, and fat.