Histone H1 and HMG 14/17 are deposited nonrandomly in the nucleus

We have studied the assembly of histone H1 and the high mobility group nonhistones 14/17 by isopycnic analysis after crosslinking density labeled MSB cell nuclei or chromatin. Carbodiimide crosslinking produces dense poly-H1 and hybrid density H1-H2A histone dimers, indicating that new H1 is deposited nonrandomly, albeit nonconservatively relative to new core histones. Core histone-HMG crosslinking with succinimidyl propionate yields dense HMG 14 in uniformly dense particles and new HMG 17 crosslinked to both dense and light protein, implying that HMG 14 and 17 each deposit nonrandomly; but differently with respect to new core octamers. Propionimidate crosslinking yields dense H1-HMG 17 dimers, suggesting that the interactions of new 14/17 with H1 (new HMG 14-old H1, new HMG 17-new H1) are reciprocal to their interactions with the core histones.