H1 Histone Family, Member X (H1FX)

Nucleosomes consist of approximately 146 bp of DNA wrapped around a histone octamer composed of pairs of each of the four core histones (H2A, H2B, H3, and H4). The chromatin fiber is further compacted through the interaction of a linker histone, H1, with the DNA between the nucleosomes to form higher order chromatin structures.

The deduced protein contains 213 amino acids and has a calculated molecular mass of 22.5 kD. Like other H1 histones, H1X has a tripartite structure consisting of a short basic N-terminal domain, followed by a conserved central globular domain and a long basic C-terminal domain. Northern blot analysis revealed that H1X was expressed ubiquitously. Unlike mRNAs for replication-dependent histones, which are not polyadenylated, the H1X mRNA was polyadenylated.