Functional properties of axolotl transient receptor potential ankyrin 1 revealed by the heterologous expression system.

Transient receptor potential ankyrin 1 (TRPA1) from tetrapod vertebrates except rodents are activated by high temperature with a relatively clear threshold. Our recent investigation suggested that a gradual heat activation without clear threshold might be a common feature for TRPA1 of fish. To approach which animal first acquires TRPA1 as a threshold detector instead of a gradual heat sensor, here, we focused on TRPA1 from axolotls (Ambystoma mexicanum). We isolated a full-length cDNA of axolotl transient receptor potential ankyrin 1 (axTRPA1) and studied the functional properties by two-electrode voltage clamp method using Xenopus oocytes. Allyl isothiocyanate, caffeine, methyl anthranilate and carvacrol activated axTRPA1 channels. The results indicated that axTRPA1 is heat activated with the average threshold of 39.7°C, suggesting that axTRPA1 already has acquired the functional property of land animals.