Images removed due to copyright considerations. See the following: Figure 1 and Table 1 in Reed SI. 2003. Ratchets and clocks: The cell cycle nover ubiquitylation and protein turnover. Nat Rev. Mol. Cell Biol. 4: 855-864. Figure 1 in Bartek J, Lukas J. Mammalian G1-and S-phase checkpoints in response to DNA damage. Curr Opin Cell
Histones vs Nonhistone Histones are small, very basic proteins rich in lysine and arginine. The histones are the basic building blocks of chromatin structure. The nucleoids of prokaryotic cells also have proteins associated with DNA, but these proteins are quite different from the histones and do not seem to form a comparable chromatin structure. Nonhistone chromosomal proteins-The histones are accompanied