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. Author manuscript; available in PMC: 2016 Dec 1.
Published in final edited form as: J Hepatol. 2015 Jul 23;63(6):1440–1448. doi: 10.1016/j.jhep.2015.07.016

Figure 6. MRP2 protein ubiquitination and the role of ubiquitin ligase E3 GP78 in obstructive cholestasis livers and HepG2 cells.

Figure 6

(A) MRP2 was ubiquitinated in the livers of a cholestatic patient. Normal mouse IgG was used as the negative control. (B) GFP tagged ubiquitin was conjugated to MRP2 in Hek293T cells. Cells were transiently transfected with human MRP2 and GFP-control, GFP-UbWT, or GFP-UbK0 expression constructs, and collected 48 hour after transfection. (C) Ubiquitin ligase E3s GP78, TEB4 and HDR1 mRNA expression in the livers of obstructive cholestatic patients (n=30) and the controls (n=23). (D) Representative Western blot of GP78, TEB4 and HDR1 protein expression, and their densitometry analyses (fold of control group, n=23 for control group, n=30 for obstructive cholestatic group). (E) Knockdown of GP78 expression increased MRP2 protein expression in HepG2 cells stably transfected with GP78 shRNA construct, and their corresponding densitometry analysis (% of control group, n=3). C1-C4, controls; O1-O5, obstructive cholestasis liver samples.*p< 0.01; #p< 0.01 to controls.