Recombinant Human HTR1E Protein: Production & Usage Protocol

Recombinant Human HTR1E Protein is a recombinant form of the human 5-hydroxytryptamine receptor 1E (HTR1E), a G protein-coupled receptor involved in serotonergic signaling, provided by Aladdin Scientific (SKU: rp370077) to support receptor pharmacology, signal transduction studies, and drug discovery research.

Product Name

Recombinant Human HTR1E Protein

SKU

rp370077

Protein Family

G Protein-Coupled Receptor (GPCR), Serotonin Receptor Family (5-HT1 subfamily)

Species Origin

Human (Homo sapiens)

Application Areas

Receptor pharmacology, GPCR signaling assays, drug discovery, binding studies

Storage Recommendation

Avoid repeated freeze-thaw cycles; store in appropriate aliquots at -20°C or -80°C (see detailed storage section)

Background: HTR1E Biology and Research Relevance

The 5-hydroxytryptamine receptor 1E (HTR1E), also known as the 5-HT_1E receptor, is a member of the serotonin receptor superfamily and belongs to the class A G protein-coupled receptor (GPCR) family. It is encoded by the HTR1E gene in humans. Upon ligand binding, HTR1E couples predominantly to G_i/o proteins, leading to inhibition of adenylyl cyclase and reduction of intracellular cyclic AMP (cAMP) levels.

HTR1E is expressed in the human brain, including regions such as the frontal cortex and caudate nucleus, and has been implicated in neuropsychiatric disorders, pain modulation, and cognitive function. Its relatively selective distribution and pharmacological profile make it an attractive target for drug discovery programs aimed at developing novel CNS therapeutics.

Recombinant Human HTR1E Protein (SKU: rp370077) enables researchers to conduct in vitro receptor binding assays, ligand screening, structural studies, and functional GPCR assays without reliance on tissue-derived material, offering consistency and reproducibility across experiments.

Reconstitution and Storage Protocol

Materials Required:

• Sterile, deionized water or the buffer specified on the product datasheet
• Microcentrifuge tubes (low-binding recommended)
• Ice or cooling block

Reconstitution Steps:

1. Briefly centrifuge the vial at low speed (e.g., 500–1000 × g for 10–30 seconds) before opening to collect lyophilized material at the bottom.
2. Add the volume of reconstitution buffer specified on the Certificate of Analysis (CoA) or product datasheet. Gently pipette up and down; do not vortex.
3. Allow the solution to sit on ice for 5–10 minutes to ensure complete dissolution.
4. Visually inspect for complete dissolution. If particulates remain, centrifuge gently and use the supernatant.

Storage Guidelines:

• For short-term use (up to 1 week): store reconstituted protein at 4°C.
• For long-term storage: aliquot into single-use volumes and store at -20°C or -80°C. Avoid repeated freeze-thaw cycles, which can degrade protein activity and integrity.
• Adding a carrier protein (e.g., 0.1% BSA) to the storage buffer may help maintain stability for some recombinant proteins — consult the product datasheet for specific guidance.

Note: Always refer to the specific Certificate of Analysis supplied with your lot for exact reconstitution volumes, protein concentration, and storage conditions.

Quality Control and Verification

Before using Recombinant Human HTR1E Protein in downstream assays, it is recommended to perform the following quality verification steps:

1. Protein Purity Assessment
Analyze an aliquot by SDS-PAGE (reducing and/or non-reducing conditions) followed by Coomassie staining or silver staining. Compare the observed molecular weight band to the theoretical molecular weight specified on the product datasheet. A single predominant band indicates acceptable purity.

2. Western Blot Confirmation
Confirm the identity of the protein using a validated anti-HTR1E antibody. The band should appear at the expected molecular weight.

3. Protein Concentration Determination
Measure the protein concentration using a BCA assay, Bradford assay, or A280 absorbance method. Use the extinction coefficient provided on the CoA if available.

4. Functional Activity (Optional)
Where applicable, verify receptor functionality using a cAMP inhibition assay or radioligand binding assay with a known 5-HT1E ligand to confirm biological activity.

Document all QC results and retain alongside the CoA for experimental traceability.

Experimental Applications and Assay Tips

Recombinant Human HTR1E Protein is suitable for a range of in vitro research applications:

Radioligand Binding Assays: Use the recombinant protein or cell membranes overexpressing HTR1E to determine binding affinities (K_d) and inhibition constants (K_i) for candidate compounds. Ensure appropriate non-specific binding controls are included.

cAMP Functional Assays: HTR1E signals through G_i/o-mediated inhibition of adenylyl cyclase. Use a validated cAMP assay kit (e.g., HTRF- or ELISA-based) to assess agonist or antagonist activity of test compounds. Pre-stimulate cells with a known adenylyl cyclase activator (e.g., forskolin) to establish a baseline before measuring inhibition.

Ligand Screening / Drug Discovery: Incorporate the protein into high-throughput screening (HTS) workflows. Optimize assay buffer conditions (pH, ionic strength, temperature) to maximize signal-to-noise ratios.

Structural and Biophysical Studies: The recombinant protein may be used in surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), or related biophysical techniques to characterize ligand–receptor interactions.

General Tips:

• Minimize protein handling time at room temperature.
• Use low-binding plasticware to reduce adsorption losses.
• Include appropriate positive and negative controls in all assays.
• Titrate protein concentration empirically for each assay format.

Troubleshooting

The following table outlines common issues encountered when working with Recombinant Human HTR1E Protein and suggested corrective actions:

Issue	Possible Cause	Suggested Action
Low or no signal in binding assay	Protein aggregation or denaturation; insufficient protein amount	Check protein integrity by SDS-PAGE; ensure proper reconstitution; titrate protein concentration
Multiple bands on SDS-PAGE	Protein degradation; contaminating proteins	Check storage conditions; use fresh aliquots; consult CoA for expected purity specifications
High background in functional assay	Inadequate washing steps; non-specific binding	Optimize wash buffer; include BSA as blocking agent; verify negative controls
Protein precipitates after reconstitution	Reconstitution buffer incompatible; concentration too high	Use recommended buffer from datasheet; reconstitute at lower concentration and dilute
Loss of activity after freeze-thaw	Repeated freeze-thaw cycles degrading protein	Aliquot into single-use volumes before freezing; add glycerol (5–10%) as cryoprotectant if compatible

Frequently asked questions

What is the recommended reconstitution buffer for Recombinant Human HTR1E Protein?

The recommended reconstitution buffer and volume are specified on the Certificate of Analysis (CoA) supplied with each lot. Generally, sterile deionized water or a phosphate-buffered saline (PBS)-based buffer is used. Always consult your lot-specific CoA for the most accurate guidance.

How should Recombinant Human HTR1E Protein be stored to maintain activity?

Reconstituted protein should be aliquoted into single-use volumes to avoid repeated freeze-thaw cycles, which can compromise protein integrity and activity. Short-term storage (up to 1 week) can be at 4°C; for long-term storage, keep aliquots at -20°C or -80°C. Refer to the product datasheet for specific conditions.

What assay types is Recombinant Human HTR1E Protein validated for?

Recombinant Human HTR1E Protein is suitable for applications including radioligand binding assays, cAMP functional assays (G-protein signaling), ligand screening, surface plasmon resonance (SPR), and Western blot verification. Please refer to the product datasheet or contact Aladdin Scientific technical support for lot-specific validation data.

How can I verify the identity and purity of my HTR1E protein lot?

Run an aliquot on SDS-PAGE to check for a predominant band at the expected molecular weight, and confirm protein identity by Western blot using a validated anti-HTR1E antibody. The CoA provided with each lot will list the specified purity and expected molecular weight for cross-reference.

Is Recombinant Human HTR1E Protein suitable for drug discovery screening?

Yes, Recombinant Human HTR1E Protein is well-suited for drug discovery applications, including high-throughput ligand screening and binding affinity studies. Its recombinant nature ensures batch-to-batch consistency superior to tissue-derived preparations, which is critical for reproducible pharmacological profiling.

References

1. Adham N, Kao HT, Schecter LE, et al. Cloning of another human serotonin receptor (5-HT1F): a fifth 5-HT1 receptor subtype coupled to the inhibition of adenylate cyclase. Proceedings of the National Academy of Sciences. 1993.
2. Hoyer D, Clarke DE, Fozard JR, et al. International Union of Pharmacology classification of receptors for 5-hydroxytryptamine (serotonin). Pharmacological Reviews. 1994;46(2):157–203.
3. Bard JA, Zgombick J, Adham N, et al. Cloning of a novel human serotonin receptor (5-HT7) positively linked to adenylate cyclase. Journal of Biological Chemistry. 1993.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.