A dileucine motif is involved in plasma membrane expression and endocytosis of rat sodium taurocholate cotransporting polypeptide (Ntcp).
|
| Abstract |
The sodium taurocholate cotransporting polypeptide (Ntcp) is the major uptake transporter for bile salts into liver parenchymal cells, and PKC-mediated endocytosis was shown to regulate the number of Ntcp molecules at the plasma membrane. In this study, mechanisms of Ntcp internalization were analyzed by flow cytometry, immunofluorescence, and Western blot analyses in HepG2 cells. PKC activation induced endocytosis of Ntcp from the plasma membrane by ~30%. Endocytosis of Ntcp was clathrin dependent and was followed by lysosomal degradation. A dileucine motif located in the third intracellular loop of Ntcp was essential for endocytosis but also for processing and plasma membrane targeting, suggesting a dual function of this motif for intracellular trafficking of Ntcp. Mutation of two of five potential phosphorylation sites surrounding the dileucine motif (Thr225 and Ser226) inhibited PKC-mediated endocytosis. In conclusion, we could identify a motif, which is critical for Ntcp plasma membrane localization. Endocytic retrieval protects hepatocytes from elevated bile salt concentrations and is of special interest, because NTCP has been identified as a receptor for the hepatitis B and D virus.
|
|---|---|
| Authors | Claudia Stross, Stefanie Kluge, Katrin Weissenberger, Elisabeth Winands, Dieter Häussinger, Ralf Kubitz |
| Journal | American journal of physiology. Gastrointestinal and liver physiology (Am J Physiol Gastrointest Liver Physiol) Vol. 305 Issue 10 Pg. G722-30 (Nov 15 2013) ISSN: 1522-1547 [Electronic] United States |
| PMID | 24008362 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't) |
| Chemical References |
|
| Topics |
|
Join CureHunter, for free Research Interface BASIC access!
Realize the full power of the drug-disease research graph!