Acid sensing ion channels (ASICs) belong to the super-family of degenerin (DEG) / epithelial sodium channels (ENaCs) and are excitatory neuronal cation channels. Like their DEG and ENaC relatives, ASICs appear to be tetramers of subunits consisting of two transmembrane domains (M1 and 2), intracellular N- and C-termini and a single, large extracellular loop. They are involved in pathophysiological processes related to extracellular pH fluctuation such as nociception, ischemia, perception of sour taste and synaptic transmission. The spider peptide toxin Psalmotoxin 1 (PcTx1) has previously been shown to inhibit specifically homo-multimers of the proton-gated cation channel ASIC1a.