| Budget Amount *help |
¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1987: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1986: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Research Abstract |
We recently described the isolation of mutant KB cells (Cyt 1 cells)resistant to the cytotoxic effect of cytochalasin B (CB).this mutant carried an altered <beta>-actin,i.e.,<beta>'-actin (Toyama,S.,and S.Toyama,1984,Cell.37:609-614).In the present study,we have examined the functional properties of actin in Cyt 1 cells.Our results showed that increased resistance of Cyt 1 cells to CB was reflected in altered properties of actin itself.This was shown directly by three findings.Firsd,the nuclei-induced polymerrization of Cyt actin was not inhidited by 2<micrn>M CB.Second,extracts from Cyt 1 cells could form dels in the presence of higher concentration of CB,as compared with extracts from parental KB cells.Third,Cyt actin bound less CB than KB actin.The functional altrtation of actin in Cyt 1 cells was further supported by the observation that,although treatment of KB cells with CB increased the pool of unpolymerized actin,the same treatment did not affect the pool of unpolymerized actin Cyt 1 cells,and that microfilaments of Cyt 1 cells were more resistant to the disrupting action of CB than those of KB cells.We conclude from these studies that the primary site of action of CB on cellular motility processes is actin.
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