This domain is found in fungal tRNA ligases and has cyclic phosphodiesterase activity [1]. tRNA ligases are enzymes required for the splicing of precursor tRNA molecules containing introns.

1: Genetic and biochemical analysis of the functional domains of yeast tRNA ligase. Sawaya R, Schwer B, Shuman S; J Biol Chem 2003;278:43928-43938. PMID:12933796