Component of the telomerase ribonucleoprotein (RNP) complex that is essential for the replication of chromosome termini (By similarity). Required for normal embryonic development (PubMed:19414594). Plays a role in nonsense-mediated mRNA decay. May form homooligomers (By similarity). Associated component of the telomerase holoenzyme complex (By similarity). Expressed during early cleavage, gastrulation and at 1 day post-fertilization. The PINc domain confers endonuclease activity and is expected to bind the catalytic metal ion. Morpholino knockdown leads to a phenotype ranging in severity from weak to severe that are developmentally delayed with disturbed brain patterning, necrosis in areas of the brain, aberrant eye development, impaired somitogenesis resulting in stacked somites, perturbed yolk sac extension and posterior axis extension with a high mortality rate of 93% at 5 days post-fertilization.