HP1BP3 is a 553 amino acid nuclear and chromosomal protein that exists as a component of heterochromatin. As such, HP1BP3 is involved in chromatin function and structure. Existing as four alternatively spliced isoforms, HP1BP3 undergoes post-translational phosphorylation, most likely by either ATM or ATR. HP1BP3 contains three H15 (linker histone H1/H5 globular) domains and is encoded by a gene that maps to human chromosome 1p36.12. Human chromosome 1 spans 260 million base pairs, contains over 3,000 genes, comprises nearly 8% of the human genome and houses a large number of disease-associated genes, including those that are involved in familial adenomatous polyposis, Stickler syndrome, Parkinson’s disease, Gaucher disease, schizophrenia and Usher syndrome.