PURIFICATION AND CHARACTERIZATION OF A HEAVY-METAL-MODULATED NUCLEAR-PROTEIN FROM SV40-TRANSFORMED CELLS

Sodium arsenite was found to stimulate an SV40-transformed BALB/c cell line (SVT2) to synthesize a 31-kDa protein within 2.5 h. This SVT2 pr otein was purified to homogeneity. It is a nuclear protein which appea rs to be associated with membranes because it is not extractable from nuclear membrane preparations by 2 M salt. It is highly hydrophobic, e luting from a reverse-phase HPLC column at a similar acetonitrile conc entration as a previously described 31-kDa BALB/c-3T3 cell nuclear pro tein. However, digestion of highly purified BALB/c-3T3 and SVT2 cell p roteins with V8 protease revealed nonidentical fragmentation patterns. Moreover, amino acid analysis of the two proteins was also dissimilar , indicating different primary structures. Thus, these two nuclear mem brane associated proteins appear to be distinct species.