The C-terminal region as a modulator of rNa(v)1.7 and rNa(v)1.8 expression levels.

Mammalian cells poorly express rNa(v)1.8 channels. In contrast, rNa(v)1.7 dorsal root ganglion channels have 90-fold higher peak Na(+) current densities. We investigated the role of rNa(v)1.7 and rNa(v)1.8 carboxy-termini in modulating the expression of rNa(v)1.7 and rNa(v)1.8 channels in tsA201 cells. Mutations in the ubiquitination site of the C-terminus did not improve rNa(v)1.8 current levels. However, rNa(v)1.8 chimeras containing the entire or the proximal portion of the rNa(v)1.7 C-terminus expressed 3.2-fold and 4.8-fold higher peak current densities, respectively, than parent rNa(v)1.8 channels. We conclude that the two Na(+) channels may have different endoplasmic reticulum processing signals.