This is a P-loop NTPase involved in antiviral immunity in bacteria. Members of this entry have a pair of transmembrane helices inserted into the P-loop NTPase domain [1].

1: A novel family of P-loop NTPases with an unusual phyletic distribution and transmembrane segments inserted within the NTPase domain. Aravind L, Iyer LM, Leipe DD, Koonin EV; Genome Biol 2004;5:R30. PMID:15128444