The protein encoded by this gene is one of two human homologs of Saccharomyces cerevisiae Rad23, a protein involved in nucleotide excision repair (NER). This protein was found to be a component of the protein complex that specifically complements the NER defect of xeroderma pigmentosum group C (XP-c) cell extracts in vitro. This protein was also shown to interact with, and elevate the nucleotide excision activity of 3-methyladenine-DNA glycosylase (MPG), which suggested a role in DNA damage recognition in base excision repair. This protein contains an N-terminal ubiquitin-like domain, which was reported to interact with 26S proteasome, and thus this protein may be involved in the ubiquitin mediated proteolytic pathway in cells.[7]
The complex of XPC-RAD23B is the initial damage recognition factor inglobal genomic nucleotide excision repair (GG-NER). XPC-RAD23B recognizes a wide variety of lesions that thermodynamically destabilize DNA duplexes, including UV-induced photoproducts (cyclopyrimidine dimers and 6-4 photoproducts ), adducts formed by environmental mutagens such as benzo[a]pyrene or various aromatic amines, certain oxidative endogenous lesions such as cyclopurines and adducts formed by cancer chemotherapeutic drugs such as cisplatin. The presence of XPC-RAD23B is required for assembly of the other coreNER factors and progression through the NER pathway both in vitro and in vivo.[8] Although most studies have been performed with XPC-RAD23B, it is part of a trimeric complex with centrin-2, a calcium-binding protein of the calmodulin family.[8]
A deficiency in expression of a DNA repair gene increases the risk for cancer (seeDeficient DNA repair in carcinogenesis). The expression of RAD23B is reduced in tumor tissue of women with breast cancer.[13] A low percentage of RAD23B positive nuclei in high grade breast cancer was also observed.[14]
RAD23B was substantially reduced by promoter methylation in a cell line derived from multiple myeloma.[9] and reduced by promoter methylation in a small proportion of non-small cell lung cancer (NSCLC) tumours.[10]
RAD23B appears to be one of 26 DNA repair genes that are epigenetically repressed in various cancers (seeCancer epigenetics).
^Linge A, Maurya P, Friedrich K, Baretton GB, Kelly S, Henry M, Clynes M, Larkin A, Meleady P (Jul 2014). "Identification and functional validation of RAD23B as a potential protein in human breast cancer progression".Journal of Proteome Research.13 (7):3212–22.doi:10.1021/pr4012156.PMID24897598.
^Wang G, Sawai N, Kotliarova S, Kanazawa I, Nukina N (Jul 2000). "Ataxin-3, the MJD1 gene product, interacts with the two human homologs of yeast DNA repair protein RAD23, HHR23A and HHR23B".Human Molecular Genetics.9 (12):1795–803.doi:10.1093/hmg/9.12.1795.PMID10915768.
Maruyama K, Sugano S (Jan 1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides".Gene.138 (1–2):171–4.doi:10.1016/0378-1119(94)90802-8.PMID8125298.
Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A, Sugano S (Oct 1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library".Gene.200 (1–2):149–56.doi:10.1016/S0378-1119(97)00411-3.PMID9373149.
Wang G, Sawai N, Kotliarova S, Kanazawa I, Nukina N (Jul 2000). "Ataxin-3, the MJD1 gene product, interacts with the two human homologs of yeast DNA repair protein RAD23, HHR23A and HHR23B".Human Molecular Genetics.9 (12):1795–803.doi:10.1093/hmg/9.12.1795.PMID10915768.
Lee SM, Li ML, Tse YC, Leung SC, Lee MM, Tsui SK, Fung KP, Lee CY, Waye MM (Sep 2002). "Paeoniae Radix, a Chinese herbal extract, inhibit hepatoma cells growth by inducing apoptosis in a p53 independent pathway".Life Sciences.71 (19):2267–77.doi:10.1016/S0024-3205(02)01962-8.PMID12215374.
