Anti-Ku antibody

Anti-Ku antibodies were reported by Mimori et al. In 1981. They found that the serum of a patient with systemic sclerosis / polymyositis overlap syndrome (Ku) precipitated a DNA-binding protein. This nuclear protein is called Ku antigen, which is sensitive to trypsin, but is not destroyed by DNase and RNAse; heating (37 ° C for 30min or 56 ° C for 15min) and pH change (pH≥10 or <6) can make its antigenicity lost. The protein portion of the Ku antigen consists of two subunits, p70 and p80 (molecular weights of 70 kD and 80 kD or 66 kD and 86 kD, respectively), forming a heterodimer, which non-covalently binds to the dsDNA ends, gaps and nicks, and participates in Repair after DNA breaks. Ku protein is the DNA-binding part of DNA-dependent protein kinases and catalyzes the phosphorylation of RNA polymerase II and other transcription factors. Ku antigen is widely present in human, calf and rabbit tissues. The molecular weight of the crude Ku antigen measured by gel filtration method was 300 kD, and the purified Ku antigen was 173 ± 21 kD by polyacrylamide gel electrophoresis; the molecular weight estimated by electron microscopy was about 160 kD. Human anti-Ku antibodies do not react with guinea pig, rat, and mouse cells.