Histone lysine residue (H-Lys)

Histone lysine residues are fundamental sites for post-translational modifications (PTMs) that dictate the structural state of chromatin and the accessibility of the genome for transcription. Located primarily on the flexible N-terminal tails of histone proteins H2A, H2B, H3, and H4, these residues can be modified by acetylation, methylation, ubiquitination, and sumoylation [1]. These modifications function as a "histone code," where specific combinations of marks are recognized by "reader" proteins to either promote an open, transcriptionally active chromatin state or a condensed, inactive state [2, 3]. In many diseases, particularly various forms of cancer, the enzymes responsible for adding or removing these modifications are mutated or overexpressed, leading to aberrant gene silencing or activation [4]. Therapeutic intervention focuses on small molecules that inhibit these enzymes or block the reader proteins from binding to the modified lysine residues, thereby restoring normal epigenetic signaling [5]. Consequently, histone lysine residues serve as the critical substrate for a wide array of epigenetic drugs currently in clinical use or development.

Other names

Histone lysineK-residueHistone tail lysineLysine side chainEpigenetic lysine site

Modulation of post-translational modifications on histone lysine residues by inhibiting writer, eraser, or reader proteins to regulate gene expression.