One hundred pl aliquots of the dialyzed MAT preparations of Fig. 1 were incubated with the telomerase antibody in the ratios of enzyme protein to telomerase antibody 12:1, 3:1, and 1:1 in the ice bath for 1 h. Twenty five pl aliquots were withdrawn for the assay of MAT activity as described in Table 1. Twenty pl of protein G PLUS-agarose suspension was then added to each tube to incubate at 4o C for 1 h. Tubes were constantly shaken during the incubation with protein G-PLUS-agarose. Protein G-PLUS-agarose was sedimented by centrifugation at 5,000 × g for 5 min. Twenty five pl aliquots were again withdrawn from the supernatant for the assay of MAT activity to determine the percent of activity remaining in the supernatant. Data are presented as CPM (% of the total CPM detectable before centrifugation).