Telomerase nucleotide addition processivity is affected by dGTP levels. (A) Schematic illustrating three possible alignments for a telomere ending in -TGGTG with the template region of TLC1. Following reverse transcription and extension of the telomere (with added nucleotides shown in orange), the number of TG dinucleotides between the TGG motif and the following TGGG motif will vary. (B and C) For strains of the indicated genotypes, telomere VI-R was amplified by PCR, cloned, and sequenced. (B) The frequency of having 0, 1, 2, or 3 and higher TG dinucleotides between a TGG and the following TGGG was plotted for each strain. (C) The frequency of having 0, 1, or 2 and higher TG dinucleotides between a TGGG and the following TGGG was plotted for each strain.