Mechanism of capsaicin entry into buried vanilloid sites in TRPV1.

The transient receptor potential vanilloid 1 (TRPV1) receptor is a promising target for nonopioid analgesics, yet hyperthermic side effects have hindered drug development. The prevailing perspective maintains that extracellular hydrophobic vanilloid ligands, such as capsaicin, traverse the cell membrane to reach the buried vanilloid site during TRPV1 activation. Here, we present an alternative mechanism based on computational and experimental approaches, which suggests a distinct hydrophobic pathway at the TRPV1-cell membrane interface as the principal route for ligand entry to the vanilloid site, rather than direct membrane penetration. Modifications to residues within this pathway greatly delayed capsaicin entry without directly modulating TRPV1 channel gating. A compound designed to occupy this pathway's entrance exhibited analgesic effects without inducing hyperthermia. Cryo-electron microscopy confirmed binding to TRPV1 and its role in perturbing capsaicin entry. Thus, our findings unveil a unique and targetable route for capsaicin access to the TRPV1 vanilloid site.