Effect of conditioned medium depleted of PCSK9-His on the internalization of LDL. His-tagged PCSK9 was cleared from conditioned medium of HepG2 cells transiently transfected with empty plasmid, wild-type (WT)-PCSK9-His plasmid or D374Y-PCSK9-His plasmid, by affinity chromatography. Conditioned medium from HepG2 cells transfected with D374Y-PCSK9-FLAG was also subjected to affinity chromatography as a control for a PCSK9 fusion protein which does not bind specifically to the nickel-chelating resin. The effect on internalization of LDL of the conditioned media before and after affinity chromatography, was studied by flow cytometry in untransfected HepG2 cells incubated with these media. Results represent mean (± SD) of four experiments. P-values are from comparisons between conditioned medium from transfections with empty plasmid on one hand and the PCSK9-containing media on the other hand (* p < 0.05, ** p < 0.01, *** p < 0.001).
Holla et al. BMC Cell Biology 2007 8:9 doi:10.1186/1471-2121-8-9