IMPROVING SCFV ANTIBODY EXPRESSION LEVELS IN THE PLANT CYTOSOL

Expression of single-chain antibody fragments (scFvs) in the plant cyt osol is often cumbersome. It was unexpectedly shown that addition at t he C-terminus of the ER retention signal KDEL resulted in significantl y improved expression levels. In this report the cytosolic location of the scFv-CK was confirmed, excluding possible mistranslocation to oth er subcellular compartments. It was shown that expression of several o ther scFvs was also improved in tobacco protoplasts. In addition expre ssion was improved in transgenic potato. Changing from KDEL to KDEI di d not affect the enhanced protein expression level. Addition of the KD EL motif is a simple and straightforward tool to stabilize in planta c ytosolic expression of many scFvs. (C) 1997 Federation of European Bio chemical Societies.