M2 Proton Channel: Difference between revisions

The M2 proton channel from influenza A is 97 amino acid residues and forms a 24-residue N-terminal extracellular domain, a 19-residue trans-membrane domain, and a 54-residue C-terminal cytoplasmic domain [wu et al]. The 19-residue TM domain forms the highly selective proton channel.<ref name="Takeuchi">PMID:12972149 </ref> Circular dichroism spectra has shown the TM domain to form an <scene name='User:Sarah_Henke/Sandbox_1/Momomer/2'>α-helix</scene> that spans the membrane.<ref name="Wu" /> By analytical ultracentrifugation, the TM domain is found to form <scene name='User:Sarah_Henke/Sandbox_1/Alpha_hlix/1'>homotetramers</scene> which contains four identical α-helices.<ref name="Takeuchi" /> Secondary structure is color coded by {{Template:ColorKey_Alpha Helicies}} This tetrameric bundle of the TM domain is found by NMR to be tilted by 25-38° from the channel axis.<ref name="Takeuchi" /> The trameric helices form a left-handed bundle that resembles a truncated cone.<ref name="Stouffer" /> The TM helicies are arranged around the channel pore with an approximate fourfold rotational symmetry.<ref name="Takeuchi" />