Proteins of BrdU-dependent hamster cell lines as characterized by two-dimensional gel electrophoresis

Cell lines which exhibit the BrdU-dependent phenotype (B4 and HAB) were studied with respect to BrdU-induced alterations in genetic expression by two-dimensional gel electrophoresis. A comparison of the proteins from the HAB cells, in which the DNA is 100% substituted by BrdU, to those of the unsubstituted parent line (3460) showed 55 protein alterations; the synthesis of 15 increased while that of the other 40 decreased. When 3460 cells were grown in BrdU such that their DNA was greater than 50% substituted, 27 protein changes could be detected; of these, the synthesis of 10 increased while that of 17 decreased. A comparison of all these changes in the various cell lines showed six which were common to the BrdU-substituted cell lines. The proteins from another Syrian hamster cell line, BHK-21 (C-13) and those of HAB cells grown in thymidine or BrdC were also examined on two-dimensional gels. Although BrdU has a dramatic effect on many cellular functions, relatively few changes in the pattern of protein synthesis could be detected in these cell lines, perhaps reflecting the specialized action of this analogue on particular cellular functions.