A, acid stimulation of cells expressing ASIC1a alone (left panel), ASIC1a and STOML1 (centre panel), or ASIC1a and trSTOML1 (right panel) showing that STOML-1 inhibits ASIC1a current amplitude in an SCP2 domain-dependent mechanism (data summarised in B). C, STOML1 has no modulatory effect upon the inactivation time constant of ASIC1a. D, acid stimulation of cells expressing ASIC1b alone (left panel) and ASIC1b and STOML1 (right panel) showing that ASIC1b current amplitude is not inhibited by STOML1 (data summarised in E). F, STOML1 has no modulatory effect upon the inactivation time constant of ASIC1b. Numbers in parentheses denote the number of cells recorded from. **P < 0.01, ***P < 0.001.