biostudies-literatureShi JGuangdong Science and Technology Department (Science and Technology Department, Guangdong Province)National Natural Science Foundation of ChinaNatural Science Foundation of Guangdong ProvinceChina Postdoctoral Science FoundationGuangdong Science and Technology DepartmentNatural Science Foundation of Guangdong Province (Guangdong Natural Science Foundation)National Natural Science Foundation of China (National Science Foundation of China)436https://www.ebi.ac.uk/biostudies/studies/S-EPMC9622906biostudies-literatureUnknown8(1)Aberrant DNA damage response (DDR) axis remains the major molecular mechanism for tumor radio-resistance. We recently characterized liquid-liquid phase separation (LLPS) as an essential mechanism of DDR, and identified several key DDR factors as potential LLPS proteins, including nucleolar protein NOP53. In this study, we found that NOP53 formed highly concentrated droplets in vivo and in vitro, which had liquid-like properties including the fusion of adjacent condensates, rapid fluorescence recovery after photobleaching and the sensitivity to 1,6-hexanediol. Moreover, the intrinsically disordered region 1 (IDR1) is required for NOP53 phase separation. In addition, multivalent-arginine-rich linear motifs (M-R motifs), which are enriched in NOP53, were essential for its nucleolar localizatiCell death discoveryNOP53 undergoes liquid-liquid phase separation and promotes tumor radio-resistance.PMC96229062019B0303160032022A15150123632020A15150103142021B15150200228210377082122057821711632019A15150109012020M680138Shen XTZheng JWang YLFeng WXChen SYFeng LLFan XJZhao WWBai SMShi JYin XKQin CfalseNOP53 undergoes liquid-liquid phase separation and promotes tumor radio-resistance.Aberrant DNA damage response (DDR) axis remains the major molecular mechanism for tumor radio-resistance. We recently characterized liquid-liquid phase separation (LLPS) as an essential mechanism of DDR, and identified several key DDR factors as potential LLPS proteins, including nucleolar protein NOP53. In this study, we found that NOP53 formed highly concentrated droplets in vivo and in vitro, which had liquid-like properties including the fusion of adjacent condensates, rapid fluorescence recovery after photobleaching and the sensitivity to 1,6-hexanediol. Moreover, the intrinsically disordered region 1 (IDR1) is required for NOP53 phase separation. In addition, multivalent-arginine-rich linear motifs (M-R motifs), which are enriched in NOP53, were essential for its nucleolar localizati2022-01-01T00:00:00Z2022 Oct2025-04-04T08:45:11.473Z2025-04-04T08:45:11.473ZS-EPMC96229063631631410.1038/s41420-022-01226-8