Simplified functional model of HP1/H1 interaction (C Simplified functional model of HP1/H1 interaction (C. elegans HIS-24/HPL-1) before and after infection. Simplified functional model of HP1/H1 interaction (C. elegans HIS-24/HPL-1) before and after infection. (A) HIS-24 and HPL-1 bind to the promoters of antimicrobial genes in the wild type (no infection). During infection, levels of HIS-24K14me1 increase, resulting in release of this variant into the cytosol as a part of the immune defense. HPL-1 levels do not change. (B) Multiple sequence alignment (ClustalX) of the N termini of HIS-24 and human linker histones H1.b (H1.2) and H1.d (H1.4). Studencka M et al. Mol. Cell. Biol. 2012;32:251-265