Figure 4.

T. brucei telomerase-mediated template termination synthesis with ddNTPs. Telomerase reactions containing either [α-³²P]dGTP (A) or [α-³²P]TTP (B) and the telomerase substrate oligonucleotides indicated were tested for the effects of ddNTP chain terminators. Control reactions lacking chain terminators (lanes 1, 5, 9, 12, and 14) were compared with reactions in which dATP was substituted by ddATP (lanes 2, 6, and 10), TTP was substituted by ddTTP (lanes 3, 7, and 11), or dGTP was substituted by ddGTP (lanes 13 and 15). Size markers (lanes M) are terminal deoxynucleotidyltransferase-labeled oligonucleotides tel 6 with [α-³²P]dCTP (A) and tel 1 labeled with [α-³²P]dGTP (B). Lanes nE and nP are mock reactions lacking extract or primer, respectively.