Scientists have revealed that they have identified the "mechanoreceptor" protein that mediates the sense of touch in mammals.
Researchers at The Scripps Research Institute (TSRI) found that mice that lack the Piezo2 ion-channel protein in their skin cells and nerve endings lose nearly all their sensitivity to ordinary light touch, but retain a mostly normal sensitivity to painful mechanical stimuli.
Ardem Patapoutian, professor at TSRI and investigator with Howard Hughes Medical Institute, said that they can say with certainty that Piezo2 is the principal touch sensor in mammals.
Of the two newly identified ion-channel proteins, only Piezo2 was expressed significantly in the touch-sensing neurons that are based in the dorsal root ganglia of the spine and extend their nerve processes into the skin. That led Patapoutian to focus on it as the likely transducer for the mammalian sense of touch.
The finding suggests that the detection of light, innocuous touch--which we commonly think of as the "sense of touch"--is mediated principally by one set of nerve ends using piezo2 ion channels. By contrast, stronger, pain-causing touch sensations appear to be mediated by a less force-sensitive set of nerve ends with their own ion channel proteins, which have yet to be discovered.
The study was published in the journal Nature.