Recombinant Human GRAMD1B Protein: Research Guide

Recombinant Human GRAMD1B Protein is a research-grade recombinant protein that enables scientists to investigate the GRAM domain-containing protein 1B's role in intracellular cholesterol sensing and lipid transport at membrane contact sites.

Product Name

Recombinant Human GRAMD1B Protein

SKU

rp366660

Protein Family

GRAMD1 family; contains GRAM and StART-like lipid transfer domains

Primary Research Area

Cholesterol homeostasis, lipid transport, membrane contact site biology

Recommended Storage

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

Species

Human (Homo sapiens)

What Is GRAMD1B and Why Does It Matter?

GRAMD1B (GRAM Domain-Containing Protein 1B) is a member of the GRAMD1 protein family that localizes to the endoplasmic reticulum (ER) membrane. It contains an N-terminal GRAM domain—a lipid-binding module that senses accessible cholesterol at the plasma membrane—and a C-terminal StART-like (steroidogenic acute regulatory protein-related lipid transfer) domain responsible for non-vesicular cholesterol transport.

GRAMD1B functions at ER–plasma membrane (ER–PM) contact sites, where it cooperates with other GRAMD1 family members (GRAMD1A and GRAMD1C) to extract and redistribute excess cholesterol from the inner leaflet of the plasma membrane to the ER. This process is integral to cholesterol homeostasis, and dysregulation of GRAMD1 proteins has been linked to alterations in cellular lipid balance relevant to cardiovascular disease, neurological conditions, and cancer biology.

Recombinant Human GRAMD1B Protein produced under controlled laboratory conditions provides researchers with a reliable tool for in vitro biochemical assays, structural studies, protein–lipid interaction analyses, and antibody validation.

Reconstitution and Storage Guidelines

Reconstitution: Prior to use, briefly centrifuge the vial to collect lyophilized material at the bottom. Reconstitute the protein in sterile, ultrapure water or an appropriate physiological buffer (e.g., PBS, pH 7.4) to a stock concentration of 0.1–1.0 mg/mL. Gently pipette to mix; do not vortex, as shear forces can denature the protein. Allow the solution to equilibrate for 10–15 minutes at room temperature before use.

Storage conditions: Store lyophilized protein at -20 °C or -80 °C upon receipt. Once reconstituted, prepare single-use aliquots to avoid repeated freeze-thaw cycles that reduce activity. Reconstituted protein is stable for up to 1 week at 4 °C and for longer periods at -80 °C with a carrier protein (e.g., 0.1% BSA) added as a stabilizer.

Important: Actual storage conditions and stability data specific to lot rp366660 should be confirmed against the Certificate of Analysis (CoA) provided with the shipment.

Experimental Applications

Recombinant Human GRAMD1B Protein is suitable for a range of in vitro research applications:

• Lipid transfer assays: Use to study non-vesicular cholesterol transport between donor and acceptor membrane vesicles in fluorescence-based or radiolabeled assay formats.
• Protein–protein interaction studies: Employ in co-immunoprecipitation, pull-down, or surface plasmon resonance (SPR) experiments to map interactions with other GRAMD1 family members, OSBP-related proteins, or VAPA/VAPB tethering proteins.
• Structural biology: Suitable as an antigen for antibody production or as a substrate for X-ray crystallography and cryo-EM studies focused on the GRAM or StART-like domain.
• ELISA and Western blot standard: Use as a positive control or quantitative standard for immunoassays detecting endogenous GRAMD1B.
• Binding assays with lipid probes: Characterize cholesterol or phosphoinositide binding affinity using fluorescently labeled lipid probes in plate-based or liposome binding formats.

Researchers should optimize protein concentrations and buffer conditions empirically for each application.

Quality, Purity, and Validation

Aladdin Scientific's Recombinant Human GRAMD1B Protein (rp366660) is manufactured under stringent quality-control processes. Researchers should review the Certificate of Analysis (CoA) for each specific lot, which documents purity (typically assessed by SDS-PAGE and/or HPLC), identity confirmation (e.g., mass spectrometry or Western blot), endotoxin levels (LAL assay), and bioactivity where applicable.

Key quality parameters to confirm from the CoA:

• Purity (%): typically ≥90% as assessed by reducing SDS-PAGE
• Endotoxin level: typically <1.0 EU/µg (important for cell-based assays)
• Host expression system (e.g., E. coli, baculovirus/insect cells, or HEK293 mammalian cells)
• Tag information (e.g., His-tag, GST-tag) and tag position (N- or C-terminal)

Note: Specific purity values, endotoxin levels, expression system, and tag details for rp366660 are not confirmed in this document and must be verified against the official CoA or by contacting Aladdin Scientific technical support.

Ordering Information and Technical Support

Recombinant Human GRAMD1B Protein is available from Aladdin Scientific under SKU rp366660. To place an order, contact your local Aladdin Scientific representative, use the online ordering portal, or submit a purchase order referencing the SKU directly.

For technical questions regarding reconstitution protocols, assay optimization, or compatibility with specific experimental systems, please reach out to Aladdin Scientific's technical support team. Custom formulations or bulk quantities may be available upon request.

Always cite the lot number from your CoA in publications and internal reports to ensure full traceability and reproducibility of your experimental data.

Frequently asked questions

What is the recommended reconstitution buffer for Recombinant Human GRAMD1B Protein?

We recommend reconstituting in sterile ultrapure water or PBS (pH 7.4) to a concentration of 0.1–1.0 mg/mL. Gently pipette to mix and allow equilibration for 10–15 minutes at room temperature before use. Confirm the recommended buffer with the lot-specific CoA, as optimal conditions may vary by formulation.

How should I store the reconstituted GRAMD1B protein to maintain activity?

Aliquot the reconstituted protein into single-use volumes immediately after reconstitution and store at -80 °C. Adding a carrier protein such as 0.1% BSA can improve stability. Avoid repeated freeze-thaw cycles, as these significantly reduce protein activity and integrity.

Is Recombinant Human GRAMD1B Protein suitable for cell-based assays?

It may be suitable for certain cell-based applications; however, endotoxin levels and formulation details must be verified from the CoA before use in cell culture experiments. Low endotoxin levels (typically <1.0 EU/µg) are critical to avoid confounding inflammatory responses in sensitive cell-based assays.

What expression system is used to produce rp366660?

The specific expression system (e.g., E. coli, insect cells, or mammalian HEK293 cells) for rp366660 is not confirmed in the publicly available product description. Please refer to the Certificate of Analysis or contact Aladdin Scientific technical support for confirmed expression system and tag details.

Can GRAMD1B protein be used as a standard in ELISA for quantifying endogenous GRAMD1B?

Yes, recombinant GRAMD1B protein can serve as a quantitative standard or positive control in ELISA formats, provided the detection antibody recognizes the recombinant form. Researchers should validate cross-reactivity between the recombinant protein and the antibody before establishing a standard curve.

References

1. Naito T, et al. Movement of accessible plasma membrane cholesterol by the GRAMD1 lipid transfer protein complex. eLife. 2019.
2. Besprozvannaya M, et al. GRAM domain proteins specialize functionally distinct ER-PM contact sites in human cells. eLife. 2018.
3. Laraia L, et al. The cholesterol transfer protein GRAMD1A regulates accessible cholesterol levels in the plasma membrane. Nature Chemical Biology. 2019.

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