Source:http://linkedlifedata.com/resource/umls/id/C0674679
NCI: Encoded by human NBS1 Gene, ubiquitous expression of 754-amino acid 85 kD Nibrin occurs principally in testis, thymus, and spleen (sites of physiologic DNA double-strand breakage) and liver, lung, striated/smooth muscle, kidney, and gut (high proliferative activity). Nibrin contains a forkhead-associated domain and a C-terminal breast cancer domain. As part of the p95/NBS1/p200/p400/MRE11/RAD50 and the BASC complexes, NBS1 participates in DNA repair and meiotic recombination. Serine phosphorylation by ATM is linked to S-phase checkpoint activation. Nibrin/gamma-H2AX associate with V(D)J recombination sites in response to RAG1-mediated cleavage. Ig Class switch DNA recombination recruits NBS1/gamma-H2AX in G1. NBS1 mutations are associated with Nijmegen breakage syndrome, chromosomal instability, cancer, and cell cycle checkpoint defects. (from Swiss-Prot, OMIM, and NCI)