Figure 1

Comparison of the features encoded by pIN-KDEL, pIN-MDEL and pIN-G expression vectors. Following expression and cleavage of the Igk-chain leader sequence, pIN-G protein adopts a transmembrane orientation where HA and cMyc epitope tags and GFP have an intra-lumenal disposition in the ER and trafficking intermediates of the secretory pathway, (but extracellular at the cell surface) [34]. In contrast, the derivatives pIN-MDEL and pIN-KDEL, which lack a transmembrane (TM) anchor, are expressed as soluble proteins in the ER lumen. While pIN-MDEL escapes the ER and enters the anterograde secretory pathway, pIN-KDEL is retained in the ER by virtue of its carboxy-terminal KDEL motif.