Structural domains that comprise this superfamilies share the structure of the N-terminal catalytic domain of resolvases, one of the two unrelated recombinase families. Resolvases are characterised by the presence of an N-terminal catalytic and a dimerization domain. This N-terminal catalytic domains carries out site-specific recombination, process characterised by a strand exchange mechanism that requires no DNA synthesis or high energy cofactor since the phosphodiester bond energy is conserved in a phospho-protein linkage during strand cleavage and re-ligation (INTERPRO:IPR006119).