This entry represents the Harbinger transposase-derived proteins mostly from animals. Proteins in this family may have nuclease activity, but do not appear to have transposase activity [, ].Harbinger DNA transposons have been identified in protists, plants, insects,worms, and vertebrates. However, mammals do not have Harbinger transposons. In human, no recognisable members of Harbinger transposase superfamily are found. Instead, a widely expressed HARBI1 gene encoding a 350-amino acid protein derived from a Harbinger transposase has been identified []. The HARBI1 protein is conserved in humans, rats, mice, cows, pigs, chickens, frogs and various bony fish []. Conserved motifs, which are expected to be catalytic centres of nuclease/ligase reactions necessary for transpositions, found in the Harbinger transposases, are also well preserved in the HARBI1 proteins []. It was also proposed that these hypothetical HARBI1 nucleases are also characterised by a strong DNA-target specificity [].
This entry represents a group of Harbinger transposase-derived proteins, including HARBI1 from animals and ALP1/ALP1L from Arabidopsis. Proteins in this family may have nuclease activity, but do not appear to have transposase activity [, ]. ALP1 is a domesticated Harbinger-related nuclease that interacts genetically with several PcG and trxG components and antagonizes PcG silencing [, ].
This domain is found in proteins that are related to and are probably endonucleases of the DDE superfamily. Proteins containing this domain include the putative nuclease HARBI1. HARBI1 is a transposase-derived protein that may have nuclease activity potential. It does not have transposase activity [, ].
