Background: GPR15 and Its Ligand GPR15LG

G protein-coupled receptor 15 (GPR15) is a seven-transmembrane receptor that was originally classified as an orphan GPCR. It is expressed predominantly on T lymphocytes and plays a critical role in immune cell homing to mucosal tissues, particularly the colon and skin. GPR15 has also been identified as a co-receptor for certain HIV and SIV strains, further underscoring its immunological relevance.

GPR15LG (GPR15 Ligand, also known as C10orf99 or GPR15L) is the endogenous chemokine-like ligand for GPR15. It is a small secreted protein that directs GPR15-expressing regulatory T cells (Tregs) and effector T cells to epithelial barrier sites. Understanding GPR15LG biology is important for research into inflammatory bowel disease, skin inflammation, and mucosal immunity.

Protein Specifications and Quality

Recombinant Human GPR15LG Protein (rp365037) from Aladdin Scientific is manufactured as a research-grade recombinant protein. The product is referenced against absea catalog number PP-512. Researchers should consult the accompanying Certificate of Analysis (CoA) and product datasheet for confirmed details on the following parameters, as these may vary by lot:

• Expression System: Confirm with CoA (commonly E. coli or mammalian/HEK293 expression systems are used for chemokine-like proteins).
• Purity: Typically >90% as determined by SDS-PAGE; confirm with lot-specific CoA.
• Formulation: Confirm buffer composition, carrier protein presence (e.g., BSA), and lyophilized or liquid state from the product datasheet.
• Biological Activity: Confirm ED50 values and functional assay data from the CoA.

All specific numerical values (molecular weight, purity percentage, endotoxin level, activity units) should be verified against the current product datasheet and CoA provided with each shipment.

Reconstitution, Storage, and Handling

Proper handling of Recombinant Human GPR15LG Protein is essential to preserve biological activity. General best-practice guidelines for recombinant proteins of this class are outlined below; always defer to the product-specific datasheet for definitive instructions:

1. Reconstitution: If supplied in lyophilized form, briefly centrifuge the vial before opening. Reconstitute in sterile, deionized water or the buffer specified in the datasheet to the recommended concentration. Allow the solution to equilibrate at room temperature for 10–15 minutes, mixing gently. Avoid vortexing.
2. Working Aliquots: Prepare single-use aliquots immediately after reconstitution to minimize freeze-thaw cycles, which can degrade activity.
3. Short-Term Storage: Store reconstituted protein at 4 °C for up to 7 days.
4. Long-Term Storage: Store lyophilized material at –20 °C or –80 °C as specified. For reconstituted protein, store aliquots at –80 °C. Avoid repeated freeze-thaw cycles.
5. Carrier Protein: If your application is sensitive to BSA or other carrier proteins, request a carrier-free formulation or confirm formulation details with Aladdin Scientific technical support.

Note: All storage conditions above represent general guidance for recombinant chemokine-like proteins. Verify lot-specific instructions with the CoA.

Experimental Applications

Recombinant Human GPR15LG Protein is suitable for a range of in vitro research applications involving GPR15 biology:

• Receptor Binding Assays: Use to confirm GPR15–GPR15LG interaction in cell-based or biochemical binding studies.
• Chemotaxis / Migration Assays: GPR15LG can be used as a chemoattractant in Transwell or microfluidic migration assays using GPR15-expressing T cells or transfected cell lines.
• Functional Signaling Studies: Investigate downstream GPR15-mediated signaling cascades (e.g., calcium flux, cAMP modulation, MAPK activation) upon GPR15LG stimulation.
• Cell Homing Models: Support in vitro modeling of Treg or effector T cell recruitment to epithelial tissues.
• ELISA / Western Blot Standards: May be used as a positive control or standard in immunoassays, subject to antibody cross-reactivity confirmation.

This protein is intended for research use only and is not suitable for therapeutic, diagnostic, or veterinary applications.

Troubleshooting and Technical Tips

The following troubleshooting guidance addresses common issues encountered when working with recombinant chemokine-like proteins such as GPR15LG:

• Low or No Biological Activity: Verify that the protein was reconstituted correctly and that freeze-thaw cycles have been minimized. Confirm that target cells express functional GPR15 at sufficient surface density. Check that BSA or carrier protein in the formulation does not interfere with your assay.
• Protein Aggregation: If precipitation is observed, briefly centrifuge at low speed (300–500 × g) and use only the supernatant. Avoid high protein concentrations during reconstitution.
• High Background in Binding Assays: Include appropriate negative controls (vehicle only, GPR15-negative cells). Titrate protein concentration to determine the optimal working range.
• Endotoxin Contamination Concern: For assays sensitive to LPS/endotoxin, confirm the endotoxin level from the CoA. Use endotoxin-removal columns if necessary.

For additional technical support, contact Aladdin Scientific's technical services team with your lot number and CoA.