Heme-based water aquareceptors

Abstract

How cells sense water is of fundamental importance in biology. Higrosensation has been demonstrated in specialized sensory cells that sense extracellular moisture. Even in microorganisms, osmosensors do not sense water per se. Water-sensing mechanisms would have been necessary for organisms to migrate and survive in water-poor conditions and to evolve into multicellular organisms. Due to the potential ability of water molecules to bind to gas-binding sites in the heme-based sensing domains of gasoreceptors, I suggest that some of them could have a parallel role as protein aquareceptors. Just as gasoreceptors function in almost every cell, aquareceptors must also function in almost every cell. I think that aquareceptors must be present in the cell membrane, cytoplasm, and every organelle. I also wonder if hemoglobin could also be considered a putative aquareceptor.