This toxin acts on different isoforms of acid-sensing ion channel ASIC1 in a similar manner to psalmotoxin-1 (AC P60514). On ASIC1a homotrimer, it provokes a pH-dependent inhibition (IC(50)=39.7 nM on human and IC(50)=1.3 nM on rat channels), whereas it potentiates ASIC1b homotrimer and ASIC1a-ASIC1b heterotrimer (EC(50)=178.1 nM on human ASIC1b, EC(50)=46.5 nM on rat ASIC1b and EC(50)=17.4 nM on rat ASIC1a-ASIC1b channels). On rat ASIC1a, it acts by inhibiting channel currents by shifting the pH of half-maximal effect (pH(50)) of steady-state desensitization and activation to more alkaline values. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Monoisotopic mass. This toxin if more stable than psalmotoxin-1 (AC P60514) when challenged with either high temperature or human serum. Does not show activity on Nav1.2/SCN2A, Kv10.1/KCNH1/EAG1 and Kv11.1/KCNH2/ERG1. Belongs to the psalmotoxin-1 family.