OSTbeta

Organic solute transporter beta, also known as OST-beta, is a protein which in humans is encoded by the "OSTB" gene.
Function.
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-beta have high expression in the testis, colon, liver, small intestine, kidney, ovary, and adrenal gland.