Figure 4.

Sequence analysis of coding joins rescued from Ku70^−/− ES cells in V(D)J recombination assay. (A) Diagram of a region in the pJH290 substrate vector that contains coding sequences. “Lac” box represents the lac operon promoter. “CAT” box represents the chloramphenicol acetyltransferase gene. The CAT gene is expressed only after the transcription terminator (OOP) is removed by recombination involving the joining of RSs (triangles). (B) Sequence of coding joins. In pJH290 coding sequence is assembled by “cut and join.” In Ku70^+/−, coding sequences are obtained from randomly picked Amp^r Cam^r clones recovered from Ku70^+/− ES cells. In Ku70^−/−, coding sequences come from 16 Amp^r Cam^r clones recovered from Ku70^−/− ES cells. The number on the right column indicates the number of duplicate sequences recovered from the transfection experiments; all came from different experiments except the five marked by an asterisk, which came from the experiment I in Table 1. Ambiguous nucleotides are underlined. Nucleotides with parentheses can be P elements.