The conserved TRPV1-CT sequence is necessary for interaction of full-length TRPV1 with Ca²⁺–CaM. (A) Tryptophan 787 is necessary for the interaction of full-length TRPV1 with Ca²⁺–CaM. Detergent-soluble fractions of HEK293 cells expressing wild-type, K155A, or W787A FLAG-tagged TRPV1 were incubated with CaM-agarose beads in the presence of EDTA or CaCl₂ and washed, and the bound fractions were eluted and analyzed by Western blot using anti-FLAG antibody. Shown is a representative result of three independent experiments. (B) Sequence alignment of the rat TRPV1-CT35 region with representative mammalian and avian species shows that the region is highly conserved (sequence identity over the whole protein sequence of rat TRPV1 vs. mouse, human, guinea pig, bovine, rabbit, chicken, and bat splice variants [long and short] TRPV1 is 96, 86, 89, 86, 87, 67, 86, and 87%, respectively). Nonconserved residues are shaded gray. The region visible in the crystal structure (residues 784–798) and the helical region (788–796) are indicated above the alignment (cyan).