Contribution of the putative inner-pore region to the gating of the transient receptor potential vanilloid subtype 1 channel (TRPV1).

The transient receptor potential vanilloid receptor-1 (TRPV1) is a sensory neuron-specific nonselective cation channel that is gated in response to various noxious stimuli: pungent vanilloids, low pH, noxious heat, and depolarizing voltages. By its analogy to K+ channels, the S6 inner helix domain of TRPV1 (Y666-G683) is a prime candidate to form the most constricted region of the permeation pathway and might therefore encompass an as-yet-unmapped gate of the channel. Using alanine-scanning mutagenesis, we identified 16 of 17 residues, that when mutated affected the functionality of the TRPV1 channel with respect to at least one stimulus modality.

Reducing and oxidizing agents sensitize heat-activated vanilloid receptor (TRPV1) current.

We have previously reported that the reducing agent dithiothreitol (DTT) strongly increases thermally induced activity of the transient receptor potential vanilloid receptor-1 (TRPV1) channel. Here, we show that exposure to oxidizing agents also enhances the heat-induced activation of TRPV1. The actions of sulfhydryl modifiers on heat-evoked whole-cell membrane currents were examined in TRPV1-transfected human embryonic kidney 293T cells.

Gadolinium activates and sensitizes the vanilloid receptor TRPV1 through the external protonation sites.

Gadolinium is a recognized blocker of many types of cation channels, including several channels of the transient receptor potential (TRP) superfamily. In this study, we demonstrate that Gd(3+), in addition to its blocking effects, activates and potentiates the recombinant vanilloid receptor TRPV1 expressed in HEK293T cells. Whole-cell currents through TRPV1 were induced by Gd(3+) with a half-maximal activation achieved at 72 microM at +40 mV.

The phosphatase activity of the isolated H4-H5 loop of Na+/K+ ATPase resides outside its ATP binding site.

The structural stability of the large cytoplasmic domain (H(4)-H(5) loop) of mouse alpha(1) subunit of Na(+)/K(+) ATPase (L354-I777), the number and the location of its binding sites for 2'-3'-O-(trinitrophenyl) adenosine 5'-triphosphate (TNP-ATP) and p-nitrophenylphosphate (pNPP) were investigated. C- and N-terminal shortening revealed that neither part of the phosphorylation (P)-domain are necessary for TNP-ATP binding. There is no indication of a second ATP site on the P-domain of the isolated loop, even though others reported previously of its existence by TNP-N(3)ADP affinity labeling of the full enzyme.

Functional role of C-terminal cytoplasmic tail of rat vanilloid receptor 1.

The vanilloid receptor [transient receptor potential (TRP)V1, also known as VR1] is a member of the TRP channel family. These receptors share a significant sequence homology, a similar predicted structure with six transmembrane-spanning domains (S1-S6), a pore-forming region between S5 and S6, and the cytoplasmically oriented C- and N-terminal regions. Although structural/functional studies have identified some of the key amino acids influencing the gating of the TRPV1 ion channel, the possible contributions of terminal regions to vanilloid receptor function remain elusive.