Acid-sensing ion channels (ASICs) are H+-activated members of the Na+-selective DEG/ENaC superfamily of ion channels. ASICs are expressed in peripheral sensory neurons, where they are believed to play a role in mechanosensation. In C.elegans, DEG/ENaC-channels are necessary for normal touch sensation. They interact with homologs of the mammalian protein stomatin to form mechanosensitive complexes. Stomatin is a ubiquitously expressed integral membrane protein in mammals. Recently it was shown that stomatin modulates specific ASIC subunits. The most dramatic alteration was seen for ASIC3 currents, where stomatin led to an almost complete inhibition of the H+-evoked current. We could reproduce this strong inhibitory effect in Xenopus oocytes. Interestingly, we also observed that SRO (stomatin-related olfactory protein), sharing 82% sequence similarity with stomatin, binds to ASIC3 without effect on its current.To identify interacting regions between stomatin and ASIC3 responsible for the inhibitory effect, we constructed chimeras between stomatin and SRO and between ASIC3 and ASIC1a, an ASIC subunit that is not inhibited by stomatin. Additionally, we constructed truncated ASIC3 and stomatin variants. Currently, we are investigating the effects of these chimeric and truncated variants by functional expression in Xenopus oocytes.