Histone H1

linker histone H1 and H5 family
PDB rendering of HIST1H1B based on 1ghc.
Identifiers
Symbol	Linker_histone
Pfam	PF00538
InterPro	IPR005818
SMART	SM00526
SCOP2	1hst / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB 1ghc​, 1hst​, 1uhm​, 1uss​, 1ust​, 1yqa​

Histone H1 is one of the 5 main histone protein families which are components of chromatin in eukaryotic cells, and is the most variable histone in sequence across species. A variant of the histone H1 protein is the histone H5, which has a similar structure and function, but is only found in avian erythrocytes, which unlike mammalian erythrocytes, have nuclei.

A cartoon showing where H1 can be found in the nucleosome

Featuring a central globular domain and long C- and N-terminal tails, H1 is involved with the packing of the "beads on a string" sub-structures into a high order structure, whose details have not yet been solved

H1 is present in half the amount of the other four histones. This is because unlike the other histones, H1 does not make up the nucleosome "bead". Instead, it sits on top of the structure, keeping in place the DNA that has wrapped around the nucleosome. Specifically, the H1 protein binds to the "linker DNA" (approximately 80 nucleotides in length) region between the histone beads, helping stabilize the zig-zagged 30 nm chromatin fiber.

H1 histone seals off the nucleosome at the location at which the linker DNA enters and leaves.

See also

• nucleosome
• histone
• chromatin.
• Other histone proteins involved in chromatin:

• H2A
• H2B
• H3
• H4