The effect of the chromosome banding techniques on the histone and nonhistone proteins of isolated chromatin

Abstract

The effect of a variety of chromosome banding techniques on the histone and nonhistone proteins of isolated, fixed, air-dried chromatin has been studied. Chromatin preparations were exposed to G-banding (SSC, urea, NaCl-urea, or trypsin), R-banding (Earle's BSS), and C-banding (NaOH or Ba(OH)2) treatments, and the proteins extracted from, and those remaining in the posttreatment chromatin, were examined by SDS polyacrylamide gel electrophoresis. The results indicate that: (i) each banding treatment produces specific quantitative and qualitative changes in the proteins of chromatin; (ii) the diverse treatments producing the same type of chromosome banding have both common and unique effects on the chromosomal proteins; and (iii) the treatments producing different types of chromosome banding have substantially different effects on the chromosomal proteins. It is not known whether these protein alterations are side effects occurring coincidentally with chromosome banding, or whether they are directly involved in mechanisms of banding. Results (ii) and (iii) suggest the latter possibility is more likely. If the protein alterations occur in specific chromosome regions, they may well influence the appearance of bands on mitotic chromosomes.