Histone H4

Featuring a main globular domain and a long N-terminal tail, H4 is involved with the structure of the nucleosome of the 'beads on a string' organization.

[1][2] Histone H4 is an important protein in the structure and function of chromatin, where its sequence variants and variable modification states are thought to play a role in the dynamic and long term regulation of genes.

This evolutionary conservation suggests that the functions of histone proteins involve nearly all of their amino acids so that any change is deleterious to the cell.

There are H4 genes that are constitutively expressed throughout the cell cycle that encode for proteins that are identical in sequence to the major H4.

Translation is initiated at the 85th amino acid of the histone H4 mRNA, resulting in a 19-aa peptide (preOGP).

[9] Eukaryotic organisms can produce small amounts of specialized variant core histones that differ in amino acid sequence from the main ones.

These variants with a variety of covalent modifications on the N-terminal can be added to histones making possible different chromatin structures that are required for DNA function in higher eukaryotes.

[10] Studies have shown that H4R3 methylation by PRMT1 (a histone methyltransferase) appears to be essential in vivo for the establishment or maintenance of a wide range of “active” chromatin modifications.

H4K16 is particularly interesting because this is the only acetylatable site of the H4 N-terminal tail, and can influence the formation of a compact higher-order chromatin structure.