This is a family of Archaeal 7-TM proteins. There are 6 closely assembled TM-regions at the N-terminus followed by a long intracellular, from residues 220-590, highly conserved region, of unknown function, terminating with one more TM-region. The short 25 residue section between TMs 5 and 6 might lie on the outer surface of the membrane and be acting as a receptor (from TMHMM).