FIG. 6.

Promoterless and enhancerless substrates do not generate DβJβ signal joins. (A) Diagram of the PCR assay used for signal join detection. The locations of amplification primers (C and E) as well as the predicted sizes of PCR products from DβJβ1 and DβJβ2 rearrangements are indicated. The relative positions of flanking promoter and enhancer elements are shown in the top diagram. (B) Levels of signal joins in TDR19 transfectants harboring the indicated miniloci 48 h after tetracycline withdrawal. The relative positions of amplification products corresponding to DβJβ1 and DβJβ2 signal joins are shown at the left. Control assays for recombinase activity (VλJλ signal joins) are presented in the bottom panel. The linearity of each assay was confirmed by serial dilutions (lanes 15 to 20) of the 5′Dβ/iEκ sample shown in lane 2.