Autoantigen Ku and its role in multiple cellular processes.

Ku is a DNA binding protein composed of 70 and 80 kDa subunits which was discovered as autoantigen in a patient with scleroderma-polymyositis overlap syndrome. Ku can bind to the end of DNA and also to some internal sequences. Ku-autoantigen acts as a potential transcription factor for several RNA polymerase II genes and RNA polymerase I gene. Ku is also associated with DNA-dependent protein kinase and involved in V(D)J recombination and DNA break repair mechanisms. Ku may be involved in replication, helicase activity and cell signaling. Therefore, Ku-autoantigen is a very important cellular factor which plays important role in the multiple cellular processes.