Recombinant Human GPRASP3 Protein: Preparation & Use Protocol

Recombinant Human GPRASP3 Protein is a research-grade recombinant protein targeting G protein-coupled receptor-associated sorting protein 3, designed to support studies of GPCR trafficking, lysosomal degradation pathways, and related intracellular signaling mechanisms.

Product Name

Recombinant Human GPRASP3 Protein

SKU

rp374013

Protein Family

GPCR-Associated Sorting Protein (GASP) family

Species Origin

Human (Homo sapiens)

Intended Use

Research use only; not for diagnostic or therapeutic use

Storage Recommendation

Avoid repeated freeze-thaw cycles; store aliquots at -80 °C for long-term use

Background: GPRASP3 and GPCR Trafficking

GPRASP3 (G Protein-Coupled Receptor-Associated Sorting Protein 3), also known as GASP-3, is a member of the GASP protein family. GASP family proteins are characterized by their ability to interact with the cytoplasmic tails of G protein-coupled receptors (GPCRs) and regulate post-endocytic receptor sorting, directing internalized receptors toward lysosomal degradation rather than recycling pathways.

GPRASP3 plays a role in modulating the surface expression levels of specific GPCRs, thereby influencing downstream signaling amplitude and duration. Research into GPRASP3 has implications for understanding receptor desensitization, addiction biology, pain signaling, and other physiological processes governed by GPCR activity.

Recombinant Human GPRASP3 Protein (rp374013) provides researchers with a defined, research-grade tool to investigate these interactions in vitro and to develop assays probing GASP–GPCR binding interfaces.

Materials and Equipment Required

• Recombinant Human GPRASP3 Protein (rp374013, Aladdin Scientific)
• Sterile, nuclease-free water or manufacturer-recommended reconstitution buffer
• Phosphate-buffered saline (PBS), pH 7.4, sterile-filtered
• Carrier protein (e.g., bovine serum albumin, BSA) if required for stability in dilute solutions
• Microcentrifuge tubes (low-protein-binding, 1.5 mL)
• Calibrated micropipettes and sterile tips
• Refrigerated microcentrifuge
• -20 °C and -80 °C freezers
• Ice bucket
• UV-Vis spectrophotometer or BCA/Bradford assay kit for concentration verification

Note: Consult the product datasheet for lot-specific reconstitution buffer recommendations and concentration details.

Step-by-Step Reconstitution and Storage Protocol

Step 1 – Pre-Reconstitution Preparation

Allow the vial to equilibrate to room temperature for 10–15 minutes before opening. Centrifuge the sealed vial briefly (1,000 × g, 30 seconds) to consolidate lyophilized material at the bottom of the vial and minimize product loss upon opening.

Step 2 – Reconstitution

Add the recommended volume of sterile reconstitution buffer (refer to the product-specific datasheet for the exact volume) gently along the side of the vial. Do not vortex. Allow the solution to sit at room temperature for 5–10 minutes, then gently swirl until fully dissolved. Confirm clarity and absence of particulates before proceeding.

Step 3 – Concentration Verification

Measure protein concentration using a BCA or Bradford assay with BSA as standard, or use A280 absorbance if the extinction coefficient is provided on the datasheet. Compare to the stated concentration to confirm successful reconstitution.

Step 4 – Aliquoting

Divide the reconstituted protein into single-use aliquots using low-protein-binding microcentrifuge tubes. Aliquot volumes should match anticipated experimental needs to avoid repeated freeze-thaw cycles, which degrade protein integrity.

Step 5 – Storage

For short-term use (up to 1 week): store at 2–8 °C. For long-term storage: snap-freeze aliquots in liquid nitrogen and store at -80 °C. Avoid repeated freeze-thaw cycles (maximum 2–3 cycles). Addition of a cryoprotectant such as glycerol (5–10% final concentration) may improve stability; verify compatibility with intended downstream assays.

Application Guidelines and Quality Considerations

Recombinant Human GPRASP3 Protein is suitable for a range of in vitro research applications. Typical uses include:

• Protein–protein interaction studies: Co-immunoprecipitation (Co-IP) or pull-down assays to characterize GPRASP3 binding partners, particularly GPCR cytoplasmic tails.
• Binding and competition assays: Surface plasmon resonance (SPR), biolayer interferometry (BLI), or ELISA-based binding assays to determine binding kinetics and affinity.
• Biochemical assays: Western blot validation, mass spectrometry studies, and structural biology applications.
• Cell-free assay systems: In vitro transcription/translation validation controls.

Quality checkpoints: Prior to use, verify protein integrity by SDS-PAGE under reducing and non-reducing conditions. Evaluate activity using a functional assay relevant to the intended application. Discard any aliquot showing visible precipitation, turbidity, or evidence of microbial contamination.

This product is for research use only and is not intended for clinical, diagnostic, or therapeutic applications.

Troubleshooting

Problem	Possible Cause	Recommended Action
Protein does not dissolve completely	Insufficient reconstitution buffer volume or vortexing	Add additional buffer incrementally; gently swirl; do not vortex; allow longer equilibration time
Lower than expected protein concentration	Product loss during reconstitution or pipetting error	Centrifuge vial before opening; use low-protein-binding tubes; re-measure with alternative assay
Precipitation after freeze-thaw	Protein aggregation due to freeze-thaw stress	Centrifuge at 10,000 × g for 5 min at 4 °C and use supernatant; add cryoprotectant for future aliquots
Loss of biological activity	Protein degradation or improper storage	Use fresh aliquot; verify storage conditions; avoid prolonged exposure to room temperature
Non-specific bands on Western blot	Antibody cross-reactivity or sample overloading	Titrate protein amount; optimize antibody dilution; include appropriate positive and negative controls

Frequently asked questions

What is the recommended reconstitution buffer for Recombinant Human GPRASP3 Protein?

The recommended reconstitution buffer is specified on the product-specific datasheet accompanying each lot. In general, sterile PBS (pH 7.4) or the manufacturer-supplied buffer is used. Always consult the current datasheet for lot-specific instructions to ensure optimal protein stability and activity.

How should Recombinant Human GPRASP3 Protein be stored to maintain stability?

For short-term use (up to one week), store the reconstituted protein at 2–8 °C. For long-term storage, aliquot the protein into single-use volumes and store at -80 °C. Avoid repeated freeze-thaw cycles, as these can lead to protein aggregation and loss of activity. A cryoprotectant such as glycerol may be added to improve freeze-thaw stability, subject to compatibility with downstream assays.

What applications is Recombinant Human GPRASP3 Protein validated for?

Recombinant Human GPRASP3 Protein is suitable for in vitro research applications including protein–protein interaction studies (e.g., Co-IP, pull-down assays), binding kinetics assays (e.g., SPR, BLI, ELISA), Western blot, and cell-free biochemical assays. Specific validated applications and activity data are provided on the lot-specific product datasheet. This product is for research use only.

How can I verify the integrity of the reconstituted GPRASP3 protein before use?

Protein integrity can be assessed by SDS-PAGE under both reducing and non-reducing conditions, followed by Coomassie staining or silver staining. The expected band size should correspond to the molecular weight stated on the datasheet. Additionally, a BCA or Bradford assay should be performed to confirm protein concentration, and a functional assay appropriate to the intended use should be conducted if possible.

References

1. Simons PC et al. GASP proteins: modulators of G protein-coupled receptor trafficking and signaling. In: The Handbook of Cell Signaling, 2nd ed. General reference for GASP/GPRASP family biology. [Review — specific details to be verified against primary literature]
2. Aladdin Scientific. Recombinant Human GPRASP3 Protein, SKU rp374013. Product Datasheet. [Consult current lot-specific datasheet for validated specifications, storage conditions, and application data.]

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