Telomerase reverse transcriptase (TERT) is a subunit of the enzyme complex telomerase, which adds nucleotides to the ends of telomeres as they become shortened during cell division .Telomerase complex plays a key role in cancer formation by telomere dependent or independent mechanisms. According to statistics, human telomerase reverse transcriptase (h-TERT) is overexpressed in more than 85% of tumors with diverse histologies, with little expression in normal tissues. Expression of h-TERT correlates with activity of telomerase, which is required for the capacity for limitless replication, a hallmark of cancer. The X-Ray Repair Cross Complementing 6 (XRCC6) is high affinity receptor for TERT, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human TERT and recombinant rat XRCC6. Briefly, TERT was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to XRCC6-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-TERT pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630 nm immediately. The binding activity of recombinant TERT and recombinant rat XRCC6 was shown in Figure 1, the EC50 for this effect is 0.009 ug/mL.