Furin and proprotein convertase 7 (PC7) lymphoma PC endogenously expressedin rat liver can be resolved into distinct post-Golgi compartments

The intracellular compartmentalization in rat liver of the membrane-associa ted convertases furin and proprotein convertase 7 (PC7)/lymphoma PC (LPC) w as investigated by analytical subcellular fractionation. In control animals , both enzymes were found to localize in fractions depleted of endoplasmic reticulum, cis-Golgi and lysosomal markers, but to co-distribute with the G olgi marker galactosyltransferase and the trans-Golgi network (TGN) marker TGN38. After over-loading Golgi-derived vesicles with very-low-density lipo proteins (VLDL) by feeding rats with ethanol, the distribution of PC7/LPC w as shifted markedly towards lower densities, in contrast with those of furi n and the TGN marker. This provides support for the TGN localization of end ogenously expressed furin and indicates that, at steady state, a considerab le proportion of PC7/LPC may be associated with vesicles derived from the T GN.