(ORDO NEWS) — The molecular mechanisms of the work of visual and other receptors have already been determined, but for hearing such work has been done only recently.
It took scientists several years and tens of millions of worms to figure out the structure of the TMS-1 protein, which perceives acoustic vibrations.
Before we hear sound, acoustic waves cause the eardrum to vibrate. Through a few tiny bones, these movements are transmitted to the fluid-filled structures of the inner ear.
Fluid vibrations are sensed by hair cells, which stimulate neurons and trigger signal transmission through the nervous system.
Hair cells can be called a key part of this whole scheme: they act as receptors for the auditory system.
But if the work of visual and other receptors was studied down to the molecular level, then for hearing it remained a mystery.
A key role in the work of hair cells is played by transmembrane channel-like proteins (Transmembrane Channel-Like Proteins, TMC): they capture mechanical vibrations, triggering the occurrence of electrical signals in the nervous system.
And recently, scientists from the Oregon Health and Science University were able to determine the molecular structure of the TMC1 protein to the nearest atom.
The molecular mechanisms of this system are highly conserved and almost identical in different animals. Therefore, to obtain the TMC1 protein, biologists used the worms Caenorhabditis elegans.
It took scientists more than five years to isolate the amount of protein needed for work, during which they grew and used about 60 million nematodes.
The pure protein preparation was examined using cryoelectron microscopy to elucidate the molecular structure of TMS-1.
TMS-1 is a transmembrane protein that penetrates the cell membrane through and through. It is a dimer consisting of a pair of identical blocks.
Each dimer includes a TMS-1 key domain that forms a pore in the membrane, as well as a CALM-1 calcium-binding domain associated with TMS-1 from within the cell.
Finally, a small TMIE domain is attached to the molecule at the periphery – according to the authors, “resembling accordion handles.”
Mechanical deformation of the cell membrane puts the whole system into operation, causing the influx of calcium ions into the cell.
This causes it to release neurotransmitters and stimulate the activity of auditory neurons.
“Neuroscience has been waiting for these results for decades,” said Peter Barr-Gillespie, a prominent researcher in the mechanisms of hearing.
Now that we know how the perception of sound is arranged at the molecular level, completely new prospects are opening up for scientists and physicians in the treatment of congenital and acquired deafness.
Contact us: [email protected]