µ-TRTX-Df1a

Overview

µ-TRTX-Df1a is a research-grade protein/peptide reagent used in research settings. It is commonly applied as a tool reagent related to NaV channels and T-type Ca2+ channels biology and/or assay development. It is supplied in Lyophilized format to support flexible downstream use in RUO workflows. Researchers commonly pair it with applications such as Electrophysiology.

Key elements and design rationale

• Molecular identity: MW: 4078.6 Da, Formula: C180H246N54O45S6.
• Source / origin: Davus fasciatus (Costa Rican tiger rump) (Cyclosternum fasciatus).
• Quality attributes: Purity: ≥98% (HPLC); Bioassay tested: Yes; Sterile / endotoxin-free: No.

Modifications

Disulfide bonds location- Cys2-Cys16, Cys9-Cys21, Cys15-Cys28 Phe34 - C-terminal amidation

When used as a biochemical or pharmacological tool, results are best interpreted relative to the experimental system (species, expression level, and assay readout) and with appropriate negative and competition-style controls where relevant. This product is intended for research use only.

Biological background

µ-TRTX-Df1a (Df1a) is a 34-amino acid peptide toxin originally isolated from the venom of the tarantula Davus fasciatus. This toxin has been identified as a potent blocker of voltage-gated sodium (NaV) and calcium (CaV)3 channels1. Df1a exhibits a rank order of potency for hNaV channels as follows: 1.7 > 1.2 > 1.3 > 1.6 > 1.1 > 1.4 > 1.5, and for hCaV3 channels, the order is 3.1 > 3.3 > 3.2. Additionally, Df1a demonstrates a dual modulatory effect by simultaneously inhibiting peak current and slowing fast inactivation of NaV1.1, NaV1.3, and NaV1.5 subtypes. It also alters the voltage dependence of activation and inactivation for most NaV subtypes1. Df1a belongs to the Family 2 of NaV-targeting spider toxins (NaSpTx), characterized by an inhibitor cystine knot (ICK) motif and highly conserved N- and C-terminal regions1. ICK peptides possess a disulfide-rich structural framework that creates a "knot," imparting exceptional structural, thermal, and proteolytic stability. CaV3 are T-type, low voltage-gated calcium channels. Their electrophysiological properties include low voltage thresholds for activation and inactivation, rapid inactivation, and rebound bursting. These properties are responsible for the CaV3-mediated fine-tuned regulation of neuronal excitability in both the central nervous system (CNS) and peripheral nervous system (PNS)2. Nav channels are involved in a wide array of physiological processes. There are nine mammalian subtypes of voltage-gated sodium (NaV) channels: NaV1.1–NaV1.9. They are transmembrane proteins responsible for propagating action potentials in excitable cells, most notably nerves and muscle. These channels are considered to be important therapeutic targets for a wide variety of pathophysiological conditions such as chronic pain, cardiac arrhythmia, and epilepsy3,4. Df1a acted as an analgesic in vivo, alleviating the spontaneous pain behaviors triggered by the NaV activator OD11.

Research relevance and current trends

• Using high-specificity ligands, toxins, and engineered peptides to dissect closely related receptor/channel subtypes and signaling microdomains.
• Pairing labeled (e.g., fluorescent) proteins/peptides with advanced imaging to map surface expression, trafficking, and nanoscale organization.
• Increasing emphasis on reproducibility through standardized characterization (identity, purity, and lot QC) and transparent reporting of reagent attributes.

Common research applications

• Electrophysiology: commonly used to compare signal, binding, or functional readouts across conditions without implying a specific protocol.

Across these use cases, changes in signal or functional readout are generally interpreted as evidence of differences in target abundance, accessibility, or engagement, but alternative explanations (matrix effects, off-target interactions, or assay artifacts) should be considered.

Notes for experimental interpretation

• Assay context matters: binding assays, functional modulation, and detection workflows can yield different readouts even for the same target system.
• Target complexity: closely related family members, splice variants, and post-translational modifications can influence apparent specificity and potency.
• Matrix and sample effects: buffer composition, detergents, and biological matrices may alter stability or apparent activity; interpret with appropriate controls.
• Control concepts: include negative controls and orthogonal validation (e.g., genetic perturbation or alternative reagents) to support robust interpretation.

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