Dear George,

I don't have any papers specifically, but it is only logical that the TRPA1, which is a cold sensing ion channel, is expressed in the sensory nerve endings, which have their soma in the dorsal root ganglion embedded and isolated far (usually many cms)  away. Sensory endings is where the detection occurs and potentials are generated. Therefore if TRPA1 is located in the soma it would not be able to detect the changes in temperature. Although the mRNA and protein may still present in the soma and along the axon, it will primarily be functional at the nerve endings. You should look into papers by David Clapham for references.

best wishes,

Refik