Myosin II Regulatory Light Chain Is Required for Trafficking of Bile Salt Export Protein to the Apical Membrane in Madin-Darby Canine Kidney Cells

Human Multidrug Resistance ABCB and ABCG Transporters: Participation in a Chemoimmunity Defense System

“…The MDR3 protein colocalizes with MDR1 and with the bile salt transporter (BSEP/ ABCB11) in the apical compartment of hepatocytes. Binding of these ABC transporters to regulatory proteins such as HAX-1 and myosin II regulatory light chain (Mlc2) has also been demonstrated (47,259). These observations suggest that HAX-1, Mlc2, and possibly cortactin are involved in the trafficking of these ABC transporters.…”

The bile salt export pump

“…In addition to these pathways, the mitogenactivated kinase cascades are also involved in the posttranscriptional regulation of Bsep expression: Induction of choleresis by tauroursodeoxycholic acid or alteration of bile flow by anisosomolarity leads to canalicular insertion/ retrieval of Bsep, a process that is critically dependent on mitogen-activated kinases [83]. In addition, studies in polarized cell lines expressing Bsep revealed that HAX-1 and myosin II regulatory light chain are required for the trafficking of Bsep to the apical membrane as well as in the regulation of its abundance in the apical plasma membrane of MDCK cells [12,73]. Studies in the polarized hepatic WIF-B9 cell line indicated that Bsep undergoes a constitutive cycling between a rab11 positive compartment and the canalicular plasma membrane domain [95].…”

The Role of the Sodium-Taurocholate Cotransporting Polypeptide (NTCP) and of the Bile Salt Export Pump (BSEP) in Physiology and Pathophysiology of Bile Formation

“…This complex intracellular trafficking of Bsep not only requires correct glycosylation [225], but also proteins directly binding Bsep. Experiments in a polarized cell line revealed that Bsep needs myosin II regulatory light chain and HAX-1 for proper targeting to the apical membrane as well as for the regulation of Bsep density in the apical membrane of MDCK cells [40,242]. In the Sf9 cell system, protein kinase C α mediates phosphorlyation of mouse Bsep [238].…”