The effect of chromosome banding techniques on the proteins of isolated chromosomes

Experiments were undertaken to determine the effect of various chromosome banding treatments on the histone and nonhistone proteins of isolated, fixed, air-dried metaphase chromosomes. Chromosome preparations were exposed to G-banding (SSC, urea, NaCl-urea, or trypsin), R-banding (Earle's balanced salt solution), and C-banding (NaOH or Ba(OH)₂) treatments, and the extracted and residual proteins were examined by SDS polyacrylamide gel electrophoresis. The results indicate that each of the banding treatments induce characteristic alterations in the chromosomal proteins. The residual proteins left in chromosomes after the diverse G-banding treatments were generally similar to one another, indicating that treatments inducing the same type of banding have similar effects on the chromosomal proteins. This was also true for the two different C-banding treatments. On the other hand, the residual protein patterns seen after the G-banding treatments were strikingly different from those seen after R-banding, which in turn differed from those seen after C-banding. The treatments inducing different types of banding therefore produce markedly different effects on the chromosomal proteins. These protein alterations may have an important influence on the induction of chromosome bands.