The HtrM-Xop2/SRM complex may interact with CheB or CheR and modulate their availability to Sop1 or Sop2. Interacts with Xop2/SRM. Expressed constitutively throughout the growth phases, both in presence and absence of white light. Is lacking a methyl-accepting transducer domain found in all other photosensory transducers. Belongs to the methyl-accepting chemotaxis (MCP) protein family.