Tankyrases interact with the telomere reverse transcriptase complex (TERT). Tankyrase 1 poly-ADP-ribosylates Telomere Repeat Binding Factor 1 (TRF1) while Tankyrase 2 can poly-ADP-ribosylate itself or TRF1. The tankyrases also contain multiple ankyrin repeats that mediate protein-protein interaction (binding TRF1 and insulin-responsive aminopeptidase) and may function as a complex. Overexpression of Tank1 promotes increased telomere length when overexpressed, while overexpressed Tank2 has been shown to promote PARP cleavage- independent cell death (necrosis).