Histone H3 (mono-methyl K23) refers to histone H3 that is modified by a single methyl group at the lysine residue position 23 (K23). In biology, histone H3 is a crucial component of the nucleosome, playing a key role in the compaction of DNA and the structure of chromatin. Mono-methylation at the K23 position (mono-methyl K23) is a specific modification form of histone H3. This modification may affect chromatin structure and gene expression by altering the interactions between histone H3, DNA, and other proteins.