NAP1L3 Background Information Proper nucleosome assembly is critical for compacting DNA into chromatin. NAP1 (nucleosome assembly protein 1) is a nuclear protein that acts as a transcriptional regulator and functions in nucleosome assembly. NAP1L3 (nucleosome assembly protein 1-like 3), also known as MB20 or NPL3, is a 506 amino acid nuclear protein belonging to the nucleosome assembly protein (NAP) family. Expressed in human brain with weak expression in heart, NAP1L3 is encoded by a gene mapping to human chromosome Xq21.32, which is in close proximity to a region closely linked to several X-linked mental retardation syndromes. Containing nearly 153 million base pairs and housing over 1,000 genes, chromosome X acts in conjunction with chromosome Y to determine sex. There are a number of conditions related to an abnormal number and combination of sex chromosomes, some of which include Turner's syndrome, color blindness, hemophilia and Duchenne muscular dystrophy.
