The N-terminal domain of the resolvase family (this family) contains the active site and the dimer interface. The extended arm at the C-terminus of this domain connects to the C-terminal helix-turn-helix domain of resolvase - see Pfam:PF02796.

1: Crystal structure of the site-specific recombinase gamma delta resolvase complexed with a 34 bp cleavage site. Yang W, Steitz TA; Cell 1995;82:193-207. PMID:7628011