Voltage-gated sodium channel alpha subunit (Site 1) (NaV alpha subunit (Site 1))

The Voltage-gated sodium channel alpha subunit (Site 1) is a critical pharmacological domain located at the extracellular entrance of the sodium channel pore (Catterall, 2012, J Physiol). It is formed by the reentrant P-loops of the four homologous domains of the alpha subunit, which together constitute the selectivity filter and the outer vestibule (Stevens et al., 2011, Mar Drugs). This site is the specific target for guanidinium neurotoxins, such as tetrodotoxin (TTX) and saxitoxin (STX), which bind with high affinity to physically block the passage of sodium ions (Zhorov & Tikhonov, 2004, Proc Natl Acad Sci). By preventing sodium influx, these agents inhibit the generation and propagation of action potentials, which are essential for nerve signaling and muscle contraction (Goldin, 2001, Annu Rev Physiol). Clinically, Site 1 is of significant interest for the development of non-opioid analgesics, particularly for treating chronic and neuropathic pain (Nieto et al., 2012, CNS Neurol Disord Drug Targets). However, the primary challenge in targeting this site is achieving sufficient subtype selectivity to avoid life-threatening side effects like respiratory paralysis or cardiac arrest (Biet et al., 2006, Br J Pharmacol). Recent research focuses on using Site 1 blockers as local anesthetics or systemic treatments for cancer-related pain (Hagen et al., 2008, J Pain Symptom Manage).

Other names

Neurotoxin receptor site 1TTX-binding siteSTX-binding siteOuter pore vestibule of NaV channelsSelectivity filter region

Direct physical occlusion of the outer pore vestibule and selectivity filter, preventing sodium ion permeation and inhibiting action potential firing.