The Lipid Raft Component Stomatin Interacts with the Na Taurocholate Cotransporting Polypeptide (NTCP) and Modulates Bile Salt Uptake.

The sodium taurocholate cotransporting polypeptide (NTCP) is expressed at the basolateral membrane of hepatocytes, where it mediates the uptake of conjugated bile acids and forms the hepatocyte entry receptor for the hepatitis B and D virus. Here, we aimed to identify novel protein-protein interactions that could play a role in the regulation of NTCP. To this end, NTCP was precipitated from HA-tagged hNTCP-expressing HepG2 cells, and chloride channel CLIC-like 1 (CLCC1) and stomatin were identified as interacting proteins by mass spectrometry.

Calnexin Depletion by Endoplasmic Reticulum Stress During Cholestasis Inhibits the Na-Taurocholate Cotransporting Polypeptide.

Cholestasis-induced accumulation of bile acids in the liver leads to farnesoid X receptor (FXR)-mediated transcriptional down-regulation of the bile acid importer Na-taurocholate cotransporting protein (NTCP) and to induction of endoplasmic reticulum (ER) stress. However, whether ER stress affects bile acid uptake is largely unknown. Here, we investigated the role of ER stress on the regulation and function of the bile acid transporter NTCP.