Histone H2B (Crotonyl K11) is a specific form of post-translational modification where the histone H2B protein at lysine 11 is crotonylated, meaning a crotonyl group is added to this amino acid residue. This modification is part of the broader class of histone lysine crotonylation (Kcr), which has emerged as an important epigenetic mark with distinct functions from histone acetylation. Crotonylation involves the addition of an acyl group from an acyl-CoA donor to the ε-amino group of the lysine side chain, which is similar to other acylation modifications but differs in hydrocarbon chain length, hydrophobicity, or charge 。 This modification has been identified in various histone and non-histone proteins, where it influences RNA processing, nucleic acid metabolism, and gene expression.