1.A.6.1.17
Broad-range thermal receptor 1 protein of 431 aas and 2 TMSs, N- and C-terminal. A nonvisual and extraocular sunlight detection mechanism occurs via the broad-range thermal receptor 1 (BRTNaC1, temperature range = 33 to 48 °C) in centipede antennae. BRTNaC1, a heat-activated cation-permeable ion channel, Heat activation of BRTNaC1 exhibits strong pH dependence controlled by two protonatable sites. Physiologically, temperature-dependent activation of BRTNaC1 upon sunlight exposure comes from a striking photothermal effect on the antennae, where a slightly acidic environment (pH 6.1) of the body fluid leads to the protonation of BRTNaC1 and switches on its high thermal sensitivity. Testosterone potently inhibits heat activation of BRTNaC1 and the sunlight avoidance behavior of centipedes. This suggests a sophisticated strategy for nonvisual sunlight detection in myriapods (Yao et al. 2023).