TRANSLOCATION OF NLS-BSA CONJUGATES INTO NUCLEI OF PERMEABILIZED MAMMALIAN-CELLS CAN BE SUPPORTED BY PROTOPLAST EXTRACT - AN EXPERIMENTAL SYSTEM FOR STUDYING PLANT CYTOSOLIC FACTORS INVOLVED IN NUCLEAR IMPORT

An heterologous experimental system, which allows the study of the yet unknown cytosolic factors involved in nuclear impart of nuclear local ization signal (NLS)-containing proteins in plants, has been establish ed. The ability of plant cell extract to substitute mammalian cytosol and to promote translocation of NLS-containing proteins into nuclei of permeabilized HeLa tells was demonstrated, The results described in t he present work show that nuclear impart of fluorescently labeled BSA conjugates bearing the NLS sequence of SV40 large T antigen could be s upported by petunia fell cytoplasmic extract, This heterologous system shows the characteristic features of the homologous mammalian system, namely, is ATP dependent and is inhibited by WGA, GTP gamma S as well as by non-fluorescent NLS-BSA conjugates, The system described here o ffers an experimental method to study and characterise cytosolic facto rs which are required for nuclear import in plants. (C) 1997 Federatio n of European Biochemical Societies.