Involved in post-transcriptional regulation of gene expression. Forms a complex composed of at least MKT1L, PBP1, XAC1 and LSM12. Expressed in the procyclic and bloodstream forms (at protein level). RNAi-mediated knockdown in both the procyclic and the bloodstream form is lethal. Belongs to the XPG/RAD2 endonuclease family. Although it belongs to the XPG/RAD2 endonuclease family, only one of the seven Asp residues involved in Mg(2+) binding is conserved suggesting that it has no nuclease activity.