Catalog Number:
(89153-246)
Clearance
Supplier:
Enzo Life Sciences
Description:
Bile Salts
Bile salts are important physiological agents that serve a number of functions, including absorption, solubilization, transport and secretion of lipids. In the liver, they participate in the generation of bile flow and the secretion of cholesterol and phospholipids, such as phosphatidylcholine. When released into the intestine, they facilitate the uptake of cholesterol, fat-soluble vitamins and other lipids. Moreover, the biosynthesis of bile acids from cholesterol is the most significant pathway for the elimination of cholesterol from the body. However, because of their detergent properties, bile acids are inherently cytotoxic and disruptions in their normal transport or secretion can result in a variety of pathophysiological conditions.
BSEP
Bile formation is an important function of the liver. It is mediated by hepatocytes which generate bile flow within the bile canaliculi by continuous vectorial secretion of bile salts and other solutes across their canalicular (apical) membrane. Bile secretion is mediated by several ATP-binding cassette (ABC) transporters located in the canalicular membrane of hepatocytes. Among these ABC transporters, the bile salt export pump (BSEP or ABCB11) represents the primary, if not sole transport system for the canalicular excretion of bile salts. Bile secretory failure results in cholestasis and progressive familial intrahepatic cholestasis (PFIC) in infancy represents a group of inherited cholestatic diseases that are classified into three subtypes. One of these subtypes, PFIC II, is associated with mutations in the BSEP gene. PFIC patients with mutations in the BSEP gene have normal γ-glutamyltransferase activity, low concentrations of bile salts in bile, and an absence of bile duct proliferation. Additionally, human obesity is associated with altered cholesterol homeostasis including increased production and turnover, as well as secretion of excess cholesterol from the liver into bile.
BSEP is a multifunctional polypeptide with two homologous halves, each containing a hydrophobic membrane-ancoring domain and an ATP-binding cassette (ABC) domain. The membrane-anchoring domain is composed of six helixes buried in the lipid bilayer of the plasma membrane and the ATP binding ABCs are exposed to the cytosol. The membrane-anchoring domain helixes are thought to form channels spanning the plasma membrane.
