Differential phosphorylation of scid and wild type pre-B cell lines

The murine scid gene encodes the catalytic subunit of the DNA-dependent protein kinase (DNA-PK_CS). The scid mutation has recently been identified as a point mutation that results in an 83 amino acid truncation at the C-terminal end of the DNA-PK_CS. This mutation impairs the double-strand DNA break (DSB) repair and the V(D)J recombination coding joint formation. However, it is not clear what the physiological targets of DNA-PK_CS are, how the scid mutation affects the kinase activity of DNA-PK_CS, and how the DNA-PK_CS is involved in DSB repair and V(D)J recombination. To address these questions, we carry out biochemical analysis on several wild type and scid Abelson-MuLV transformed pre-B cell lines. Recently, we found that wild type and scid cell extracts exhibit different phosphorylation patterns involving several different proteins. We are in the process of characterizing the biochemical nature and possible functions of these proteins.