THE MODE OF ACTION OF Y13-259 SCFV FRAGMENT INTRACELLULARLY EXPRESSEDIN MAMMALIAN-CELLS

The anti-p21ras Y13-259 single-chain Fv fragment (scFv) neutralizes th e activity of p21-ras when intracellularly expressed in different syst ems. We have studied the mode of action of this inhibition in 3T3 K-ra s fibroblasts and demonstrated that (i) this antibody fragment is high ly aggregating when cytoplasmically expressed and (ii) the p21-ras ant igen is sequestered in these aggregates in an antibody-dependent manne r. This co-segregation leads to an efficient inhibition of DIVA synthe sis. These results suggest that an antigen can be diverted from its no rmal location inside the cells in an antibody mediated way, prospectin g a new mode of action for intracellular antibodies in vivo. (C) 1998 Federation of European Biochemical Societies.