Yeast chromatin: search for histone H1.

Yeast chromatin, isolated by a rapid procedure contains in addition to histones H2A, H2B, H3 and H4 a fifth major basic protein. This fifth polypeptide is not an intrinsic component of the nucleosome structure. It has properties of both histone and nonhistone proteins and might represent an early form of histone H1 and of high mobility group nonhistone proteins of higher eukaryotes. Electron microscopic visualization of isolated yeast nucleosomes substaniates further the similarity of the chromatin structudre of this unicellular eukaryote to that of higher eukaryotes.