Membrane association of NS4B carboxy terminal domain. Huh7 cells transfected with NS4B-CTD-Myc, NS4B-CTD tripleE-Myc or NS4B-CTD Helix-swop-Myc were subjected to sucrose density gradient centrifugation. Cell lysates were loaded under a sucrose gradient from 10–80% w/v and part of the lysate was used as a loading control (L). Fractions were taken from top (fraction 1) to bottom (fraction 23) and separated by SDS-PAGE. Followed by immunoblot analysis for Calnexin, Transferrin Receptor (TfR), Cytochrome C oxidase subunit IV (COX-IV) and Glyceraldehyde 3-phosphate dehydrogenase (GAPDH). NS4B-CTD and NS4B-CTD tripleE were assayed using an antibody against Myc-epitope. M indicates where molecular weight marker was loaded.