The C-Terminal of Na V 1.7 Is Ubiquitinated by NEDD4L.

Na V 1.7, the neuronal voltage-gated sodium channel isoform, plays an important role in the human body's ability to feel pain. Mutations within Na V 1.7 have been linked to pain-related syndromes, such as insensitivity to pain. To date, the regulation and internalization mechanisms of the Na V 1.7 channel are not well known at a biochemical level. In this study, we perform biochemical and biophysical analyses that establish that the HECT-type E3 ligase, NEDD4L, ubiquitinates the cytoplasmic C-terminal (CT) region of Na V 1.7. Through in vitro ubiquitination and mass spectrometry experiments, we identify, for the first time, the lysine residues of Na V 1.7 within the CT region that get ubiquitinated. Furthermore, binding studies with an NEDD4L E3 ligase modulator (ubiquitin variant) highlight the dynamic partnership between NEDD4L and Na V 1.7. These investigations provide a framework for understanding how NEDD4L-dependent regulation of the channel can influence the Na V 1.7 function.