Histone fold
Encyclopedia
A histone fold is a fold found near the C-terminus of each type histone
in a histone octamer
. The core histones share a structurally conserved motif
, the histone fold, averaging about 70 amino acid
s. The histone fold consists of three alpha helices
connected by short loops.
Histone
In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation...
in a histone octamer
Histone octamer
A histone octamer is an octamer of the histones found at the center of a nucleosome core particle. It consists of 2 copies of each of the four core histone proteins . The octamer assembles when a tetramer, containing two copies of both H3 and H4, complexes with two H2A/H2B dimers...
. The core histones share a structurally conserved motif
Structural motif
In a chain-like biological molecule, such as a protein or nucleic acid, a structural motif is a supersecondary structure, which appears also in a variety of other molecules...
, the histone fold, averaging about 70 amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s. The histone fold consists of three alpha helices
Alpha helix
A common motif in the secondary structure of proteins, the alpha helix is a right-handed coiled or spiral conformation, in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid four residues earlier...
connected by short loops.