Enzymatic Modifications and Their Possible Roles in Regulating the Binding of Basic Proteins to DNA and in Controlling Chromosomal Structure

Since the original work by Friedrich Miescher (1874) almost a hundred years ago on the chromosome-associated proteins (histones and protamines) of salmon testes and sperm, technical advances have permitted the reproducible separation of the histones into five distinct fractions (Rasmussen et al., 1962; Johns and Butler, 1962) and the elucidation of the amino acid sequences of most of the major histone fractions (DeLange and Smith, 1971; Phillips, 1971), together with some of the protamines (Ando and Watanabe, 1969). In addition, it has been recognized that these proteins can be modified enzymatically in vivo by reactions such as phosphorylation, acetylation, and methylation of specific amino acid residues (Allfrey, 1971). However, the exact functions of these proteins, their modifications, and their interactions with DNA are not known.