histonmarkering

Histonmarkering refers to post-translational modifications of histone proteins, primarily on their N-terminal tails, that influence chromatin structure and gene expression. The most studied marks include methylation and acetylation of lysine residues (for example H3K4me3, H3K27me3, H3K9ac, H3K27ac), phosphorylation (such as H3S10ph), and ubiquitination (notably H2BK120ub1). These covalent changes are installed by histone-modifying enzymes and can be dynamic or inherited through cell division.

These marks are interpreted by reader proteins, while writer enzymes add marks and eraser enzymes remove them. The combination and genomic location of histone marks contribute to what is sometimes called a histone code, influencing chromatin accessibility and the recruitment of transcriptional machinery. Active marks are generally associated with open chromatin and gene activation, whereas repressive marks correlate with compacted chromatin and gene silencing. The same histone residue can host multiple marks that interact to fine-tune transcription in a context-dependent manner.

Histone markering plays essential roles in development and differentiation, cellular memory, imprinting, and X-chromosome inactivation, and it interacts with DNA methylation and higher-order chromatin organization. Alterations in histone marks are observed in cancers and other diseases and can reflect cellular state, development stage, or environmental influences. Understanding histone marks provides insight into gene regulation mechanisms and epigenetic inheritance.

Techniques such as chromatin immunoprecipitation followed by sequencing (ChIP-seq), ChIP-chip, and newer methods like CUT&RUN are used to map histone marks across the genome. The study of histone markering is central to epigenetics and has informed the development of therapies targeting histone-modifying enzymes, including histone deacetylase inhibitors and inhibitors of histone methyltransferases.