(A and B) Direct telomerase extension assay (300 mM KCl) of endogenous telomerase purified from parental (WT) and TCAB1 knockout (A) HeLa and (B) Halo-TERT cell lines (LC1 and LC2 loading controls, n = 2 and 3, mean).
(C) Quantification of endogenous telomerase activity in samples from TCAB1 knockout cells relative to parental controls (n = 3, mean). TKO, TCAB1 knockout.
(D and E) Direct telomerase extension assay (150 mM KCl) of telomerase purified from parental (WT) and TCAB1 knockout overexpressing TERT and TR (–Ab is a no-TERT antibody control). (D) HeLa and (E) Halo-TERT cell lines (LC1 and LC2 loading controls). TKO, TCAB1 knockout.
(F) Quantification of telomerase activity in samples from TCAB1 knockout cells relative to parental controls (n = 4–7, mean, t test).
(G) Specific activity (total activity/TR in sample; see Figure 3F) of overexpressed telomerase purified from TCAB1 knockout cells relative to parental controls normalized to 1 (n = 4–7, mean, t test).