Effect of deleting residues 56C–52C from the 3′ end of the alignment domain on telomerase activity by TRAP assay. Lane 1, 1× CHAPS buffer; lane 2, TSR8 template amplification control; lane 3, wild-type telomerase from HeLa cell extracts; lane 4, RRL control (–hTR, –hTERT mRNA); lane 5, telomerase activity reconstituted from wild-type hTR; lanes 6–10, recombinant mutants Δ1, Δ2, Δ3, Δ4 and Δ5, respectively; lane 11, RRL control (+hTR, –hTERT mRNA); lane 12, RRL (–hTR, +hTERT mRNA). The internal PCR control band (I.C.) for the assay is indicated.