FIGURE 22-34 Piezo channels are mechanotransducers. (a) To identify channels that transduced mechanical information, cDNAs encoding transmembrane proteins were expressed in heterologous cells, and the response to mechanical perturbation with a glass pipette was determined by patch clamp recording (shown) or by calcium imaging (not shown). (b) When Piezo1 or Piezo2 cDNAs are expressed in cultured cells, poking the cell with a glass pipette elicits a strong inward current. (c) Piezo1 and 2 form homotetrameric cation channels. Each subunit is extremely large, with over 2000 amino acid residues and over 30 transmembrane domains. The assembled channel thus contains over 120 membrane spanning domains, and has a mass of over 1.2 million daltons (about the same mass as the small subunit of the ribosome)!

[Photo courtesy of Ardem Patapoutaian.]