Within the context of chromatin, post-translational modifications (PTM's) of histones play important roles in nearly every biologically occurring DNA-related process. Ubiquitination is one such histone PTM, and while the modification was discovered more than three decades ago, its functions are less well understood than other histone modifications such as methylation and acetylation. Polycomb Repressive Complex 1 (PRC1) is an evolutionarily conserved, multi-subunit protein that is essential for maintaining epigenetic repression of key developmental loci in embryonic stem cells (ESCs). PRC1 proteins BMI1, RNF2 and others function together as a Ubiquitin E3 ligase that specifically mono-ubiquitinates histone H2A (H2AK119u1) which effects chromatin remodeling in a heritably transmissible manner. BMI1 activity has also been reported as necessary for constitutive heterochromatin formation in mammalian somatic cells, again demonstrating that ubiquitination of histones is important in maintaining genomic integrity and transcriptional control in eukaryotes.
Produced and offered in collaboration with EpiCypher™, this mononucelosome is assembled from recombinant human histones expressed in E.coli (two each of histones H2A, H2B, H3 and H4. Accession numbers P04908, O60814, P68431 and P62805, respectively) wrapped by 147 base pairs of 601 positioning sequence DNA. There is a 5' biotin-TEG group on the DNA. Approximately 50% of the nucleosomes are mono-ubiquitinated on histone H2A lysine 118, while the other 50% are mono-ubiquitinated on both histone H2A lysine 118 and histone H2A lysine 119 (multi-mono-ubiquitination).
