Recombinant Human GRAMD2B Protein: Protocol & Usage Guide

Recombinant Human GRAMD2B Protein is a research-grade recombinant protein designed to support studies of GRAM domain-containing lipid-sensing and transfer biology in human cellular systems.

Product Name

Recombinant Human GRAMD2B Protein

SKU

rp375089

Protein Origin

Human (Homo sapiens)

Protein Class

GRAM domain-containing protein (GRAMD family)

Recommended Storage

-80°C for long-term storage; avoid repeated freeze-thaw cycles

Primary Applications

Biochemical assays, binding studies, lipid transfer research

Overview of GRAMD2B and Its Biological Significance

GRAMD2B (GRAM Domain Containing 2B) is a member of the GRAMD protein family, which is characterized by the presence of a GRAM (Glucosyltransferase, Rab-like GTPase Activators, and Myotubularins) domain and a StART-like lipid transfer domain. These proteins are implicated in lipid sensing at membrane contact sites and in the non-vesicular transport of lipids between intracellular membranes, particularly at endoplasmic reticulum (ER) and plasma membrane (PM) junctions.

Research into GRAMD family proteins has expanded our understanding of how cells maintain cholesterol and phospholipid homeostasis. GRAMD2B, like other family members, is proposed to participate in the recognition and redistribution of specific lipid species, making it a relevant target for studies in cell biology, lipid metabolism, and associated disease pathways.

Recombinant Human GRAMD2B Protein (SKU: rp375089) supplied by Aladdin Scientific provides researchers with a well-defined reagent for in vitro investigation of these functions.

Reconstitution Protocol

Follow the steps below to reconstitute Recombinant Human GRAMD2B Protein for experimental use. Always work on ice and maintain aseptic technique throughout.

1. Equilibrate the vial: Remove the vial from -80°C storage and allow it to equilibrate briefly at room temperature (no more than 5 minutes) before opening.
2. Add reconstitution buffer: Centrifuge the vial briefly (1,000 × g, 30 seconds) to collect lyophilized material at the bottom. Add the recommended volume of sterile, ultrapure water or the buffer specified on the product datasheet slowly to the side of the vial. The typical reconstitution buffer is PBS (pH 7.4) with carrier protein (e.g., 0.1% BSA) if required for stabilization.
3. Dissolve gently: Do not vortex. Gently swirl or pipette up and down to dissolve the protein. Allow 10 minutes on ice for complete dissolution.
4. Aliquot: Prepare single-use aliquots to avoid repeated freeze-thaw cycles, which degrade protein activity and integrity.
5. Store aliquots: Store working aliquots at -20°C (up to 1 month) or -80°C for longer-term storage.

Note: Specific reconstitution volume and buffer conditions should be confirmed against the lot-specific Certificate of Analysis (CoA) provided with the product.

Recommended Applications and Experimental Tips

Recombinant Human GRAMD2B Protein is suitable for a range of in vitro research applications, including but not limited to:

• Binding and interaction assays: Use in pull-down, co-immunoprecipitation, or surface plasmon resonance (SPR) experiments to study protein-lipid or protein-protein interactions involving the GRAM or StART-like domain.
• Lipid transfer assays: Incorporate into fluorescence-based or radiolabeled lipid transfer assays to evaluate the lipid transport activity of GRAMD2B in a defined biochemical system.
• Antibody validation: Use as a positive control antigen for validating GRAMD2B-specific antibodies in Western blot or ELISA formats.
• Structural studies: Serve as a substrate for biophysical techniques such as size-exclusion chromatography (SEC) or dynamic light scattering (DLS) to assess oligomeric state or conformational behavior.

Experimental tips:

• Determine the optimal protein concentration empirically for each assay type.
• Include appropriate negative controls (e.g., heat-inactivated protein) to confirm activity-specific results.
• Minimize exposure to light and oxidizing agents to preserve protein integrity.
• Consult the product CoA for purity (typically assessed by SDS-PAGE) and endotoxin levels before use in cell-based assays.

Storage, Stability, and Quality Control

Storage conditions: Store Recombinant Human GRAMD2B Protein at -80°C upon receipt for long-term stability. Once reconstituted, aliquots may be stored at -20°C for short-term use (up to 1 month). Avoid repeated freeze-thaw cycles, as these can cause protein aggregation and loss of biological activity.

Stability: Lyophilized protein is generally stable for up to 12 months from the date of manufacture when stored under recommended conditions. Reconstituted protein should be used as soon as possible. Refer to the product-specific CoA for confirmed expiry information.

Quality control: Each lot of Recombinant Human GRAMD2B Protein is subject to quality control testing prior to release. Standard QC tests typically include:

• SDS-PAGE analysis to confirm molecular weight and assess purity
• Endotoxin testing (LAL method) to ensure suitability for cell-based applications
• Protein concentration determination (e.g., by BCA or A280 measurement)

Always verify lot-specific QC data on the Certificate of Analysis included with your shipment or available through Aladdin Scientific customer service.

Troubleshooting Common Issues

The following table summarizes common issues encountered when working with Recombinant Human GRAMD2B Protein and suggested corrective actions:

• Protein does not dissolve completely: Ensure the vial was centrifuged before adding buffer. Allow more time on ice (up to 15 minutes) and pipette gently. Do not vortex.
• Low or no detected activity: Confirm the protein has not undergone excessive freeze-thaw cycles. Verify that assay conditions (pH, salt concentration, cofactors) are appropriate for GRAMD2B function. Check that the protein concentration used is within the linear range of the assay.
• Unexpected bands on SDS-PAGE: Minor additional bands may represent glycosylation variants or degradation products. Confirm with the lot CoA. If bands are substantially different from expected molecular weight, contact Aladdin Scientific technical support.
• High background in cell-based assays: Verify endotoxin levels from the CoA. Use endotoxin-free diluents and labware. Consider filtering reconstituted protein through a 0.22 µm membrane before addition to cell cultures.
• Protein aggregation: Add a carrier protein (0.1% BSA) to the storage buffer. Use fresh aliquots and avoid extended incubation at temperatures above 4°C.

Frequently asked questions

What is the recommended reconstitution buffer for Recombinant Human GRAMD2B Protein?

The recommended reconstitution buffer is typically sterile PBS (pH 7.4), with the optional addition of 0.1% BSA as a carrier protein to enhance stability. Always confirm the specific buffer and volume recommended for your lot by consulting the Certificate of Analysis (CoA) provided with the product.

How should Recombinant Human GRAMD2B Protein be stored to maintain activity?

Lyophilized protein should be stored at -80°C immediately upon receipt. Once reconstituted, prepare single-use aliquots and store at -80°C for long-term use or at -20°C for up to one month. Avoid repeated freeze-thaw cycles, as this can lead to protein aggregation and loss of activity.

What applications is Recombinant Human GRAMD2B Protein validated for?

Recombinant Human GRAMD2B Protein (rp375089) is suitable for biochemical binding assays, lipid transfer studies, antibody validation (e.g., Western blot, ELISA), and biophysical characterization. Specific application validation data should be confirmed in the product datasheet or CoA. If you require application-specific guidance, contact Aladdin Scientific technical support.

How can I determine the correct working concentration for my assay?

The optimal working concentration of Recombinant Human GRAMD2B Protein must be determined empirically for each assay format and experimental system. As a starting point, consult published literature on GRAMD family proteins or similar recombinant proteins in analogous assays. Perform a dose-response experiment using a range of protein concentrations to identify the linear response range.

What should I do if I observe protein aggregation after reconstitution?

If aggregation is observed, try adding a carrier protein such as 0.1% BSA to the reconstitution buffer. Ensure the reconstitution is performed on ice and that the protein is dissolved gently without vortexing. If aggregation persists, centrifuge at low speed (500–1,000 × g, 5 minutes, 4°C) to pellet aggregates before using the supernatant. Contact Aladdin Scientific technical support if the issue continues.

References

1. Naito T, et al. Movement of accessible plasma membrane cholesterol by the GRAMD1 lipid transfer protein complex. eLife. 2019.
2. Sandhu J, et al. Aster Proteins Facilitate Nonvesicular Plasma Membrane to ER Cholesterol Transport in Mammalian Cells. Cell. 2018.
3. Besprozvannaya M, et al. GRAM domain proteins specialize functionally distinct ER-PM contact sites in human cells. eLife. 2018.

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