FIG. 3.

Competitive primer challenge assay with hTERT T-motif mutants. Primer extension reactions were carried out under competitor challenge conditions. Following 5-min binding of the radiolabeled substrate primer, extension reactions were initiated and chased with excess cold competitor primer. Postchase aliquots were taken at 3 and 30 min and analyzed via PAGE. The prechased lane contains 30-min extension reaction mixture in which excess competitor primer was added before IVR wild-type telomerase was added. Marker sizes (in nucleotides) are indicated to the left of the gels.