Two sodium channels contribute to the TTX-R sodium current in primary sensory neurons

We have cloned a second tetrodotoxin-resistant (TTX-R) sodium channel α subunit, SNS2, with the same amino-acid sequence as a putative sodium channel α subunit NaN (ref. 1). SNS2 expression in HEK293T cells produced a TTX-R voltage-gated sodium current with faster kinetics and a lower TTX IC50 than the previously cloned sensory-neuron-specific sodium channel, SNS/PN3 (Refs 2, 3). SNS2 was co-expressed with SNS/PN3 in small DRG neurons.