ESTABLISHMENT AND CHARACTERIZATION OF AN ABRIN-RESISTANT CELL-LINE

An abrin-resistant cell line, CHOR 3-4, was isolated from CHOK1 cells which were resistant to a high concentration of abrin (160 ng/ml), and had a 1000-fold higher resistance to abrin that that of CHOK1 cells. CHOR 3-4 cells were about 25-fold more resistant than CHOK1 cells to t he N-glycosidase activity of abrin, which was measured by hydrolyzing the N-glycosidic bond of adenine 4324 nucleotide from 3' end of mammal ian 28S rRNA. However, the isolated polysomes of CHOR 3-4 cells had th e same sensitivity to abrin as those of CHOK1 cells. On measuring the binding of I-125-abrin to CHOR 3-4 cells, it was decreased to about 20 % that of CHOK1 cells. This indicates that the mechanism of the resist ance of CHOR 3-4 to abrin is due to the alteration of glycoproteins or glycolipids of cell membrane.