title: Trypsin cleaves acid-sensing ion channel 1a in a domain that is critical for channel gating.
abstract: Acid-sensing ion channels (ASICs) are neuronal Na(+) channels that are members of the epithelial Na(+) channel/degenerin family and are transiently activated by extracellular acidification. ASICs in the central nervous system have a modulatory role in synaptic transmission and are involved in cell injury induced by acidosis. We have recently demonstrated that ASIC function is regulated by serine proteases. We provide here evidence that this regulation of ASIC function is tightly linked to channel cleavage. Trypsin cleaves ASIC1a with a similar time course as it changes ASIC1a function, whereas ASIC1b, whose function is not modified by trypsin, is not cleaved. Trypsin cleaves ASIC1a at Arg-145, in the N-terminal part of the extracellular loop, between a highly conserved sequence and a sequence that is critical for ASIC1a inhibition by the venom of the tarantula Psalmopoeus cambridgei. This channel domain controls the inactivation kinetics and co-determines the pH dependence of ASIC gating. It undergoes a conformational change during inactivation, which renders the cleavage site inaccessible to trypsin in inactivated channels.
authors.affiliation: Département de Pharmacologie et de Toxicologie, Université de Lausanne, Switzerland.
authors.forename: Marija
authors.initials: M
authors.lastname: Vukicevic
authors.forename: Gilles
authors.initials: G
authors.lastname: Weder
authors.forename: Aurélien
authors.initials: A
authors.lastname: Boillat
authors.forename: Anne
authors.initials: A
authors.lastname: Boesch
authors.forename: Stephan
authors.initials: S
authors.lastname: Kellenberger
mesh_terms: D062565:Acid Sensing Ion Channels; D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D015222:Sodium Channels / Q000737:chemistry* / Q000378:metabolism; D013111:Spider Venoms; D014357:Trypsin / Q000737:chemistry / Q000494:pharmacology*; D014981:Xenopus / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: C568267:ASIC1 protein, mouse; D062565:Acid Sensing Ion Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D015222:Sodium Channels; D013111:Spider Venoms; D001120:Arginine; D014357:Trypsin