Figure 4. Transmembrane domain of ASIC1.  The transmembrane domain of ASIC1 (left) is shown with the top pointing to the extracellular region and the bottom to the cytoplasm. The blue shows hydrophilic regions, while the tan shows hydrophobic regions. A cut away view of the transmembrane domain (right) shows the ion channel. The Leu440 (red) and Gly435 (green) that provides the size specificity of the channel are labeled. PDB ascession code: 2QTS.