SECRETION OF GREEN FLUORESCENT PROTEIN FROM RECOMBINANT BACULOVIRUS-INFECTED INSECT CELLS

Trichoplusia ni (High Five) and Spodoptera frugiperda (Sf21) cells wer e engineered for expression of epitope (Flag)-tagged signal peptide-gr een fluorescent protein (GFP) fusions to examine the suitability of GF P as a secretory marker. The recombinant baculovirus-infected cells be came fluorescent, and the High Five cells but not Sf21 cells secreted GFP in the culture medium as detected by the presence in the culture s upernatant of a Flag-immunoreactive 30-kDa species and the characteris tic 510-nm GFP fluorescence peak. Signal peptides derived from ecdyste roid UDP-glucosyltransferase of Autographa californica nuclear polyhed rosis virus and from rat brain glutamate receptor were both able to pr omote secretion of GFP. GFP may thus be used as a research tool in the study of the secretory process in insect cells both in cell biology a nd in biotechnological applications. (C) 1996 Academic Press, Inc.