What Is GRAMD1C? Gene, Protein Family, and Domain Architecture

GRAMD1C (GRAM Domain Containing 1C), also known as ASTER-C, is a member of the GRAMD1 protein family that includes GRAMD1A (ASTER-A) and GRAMD1B (ASTER-B). The family is defined by the presence of a conserved GRAM (Glucosyltransferase, Rab-like GTPase Activators, and Myotubularins) domain, a central StART-like (Steroidogenic Acute Regulatory protein-related lipid Transfer) domain responsible for binding and shuttling cholesterol, and one or more C-terminal transmembrane helices that anchor the protein to the endoplasmic reticulum (ER) membrane.

The human GRAMD1C gene is located on chromosome 9 and encodes a protein that is broadly expressed across multiple tissues. At membrane contact sites between the ER and the plasma membrane, GRAMD1C senses accessible cholesterol and facilitates its non-vesicular transfer from the plasma membrane to the ER, thereby contributing to cellular cholesterol homeostasis and lipid redistribution.

Biological Functions: Cholesterol Sensing, Lipid Transport, and Metabolic Relevance

GRAMD1C plays a central role in maintaining intracellular cholesterol balance. The StART-like domain directly binds cholesterol, enabling the protein to extract excess accessible cholesterol from the inner leaflet of the plasma membrane and deliver it to the ER. Once at the ER, cholesterol can be esterified by ACAT enzymes for storage or distributed to other organelles.

The GRAM domain functions as an anionic lipid sensor, recognizing phosphatidylserine and phosphatidylinositol phosphates (PIPs) enriched in the inner plasma membrane leaflet. This lipid-sensing capacity recruits GRAMD1C to ER–plasma membrane contact sites in a cholesterol-dependent manner, coupling cholesterol availability with transfer activity.

Dysregulation of GRAMD1C-mediated cholesterol transport has been implicated in conditions associated with aberrant lipid metabolism, including atherosclerosis research models and certain cancers where altered sterol flux supports tumor cell proliferation. These associations make GRAMD1C a subject of growing interest in metabolic disease and oncology research.

Research Applications of Recombinant Human GRAMD1C Protein

Recombinant Human GRAMD1C Protein (SKU: rp369104) is suitable for a range of biochemical and cell biology research applications:

• In vitro lipid transfer assays: The recombinant protein can be used to reconstitute cholesterol transfer activity in defined liposomal systems, enabling quantitative measurement of sterol extraction and delivery kinetics.
• Protein–protein interaction studies: Co-immunoprecipitation (co-IP), pull-down assays, and surface plasmon resonance (SPR) experiments can probe GRAMD1C interactions with ER membrane proteins, other GRAMD1 family members, or regulatory factors.
• Structural biology: Recombinant GRAMD1C protein serves as an antigen for antibody generation or as a reference standard in Western blot and ELISA-based detection assays.
• Drug target validation: In the context of metabolic disease and cancer research, GRAMD1C can serve as a target for small molecule screening aimed at modulating intracellular cholesterol flux.
• ELISA and immunoassay development: High-purity recombinant protein is suitable as an immunogen or calibration standard for immunoassay development.

Handling, Storage, and Quality Considerations

To maintain the activity and integrity of Recombinant Human GRAMD1C Protein, researchers should observe the following best-practice guidelines:

• Storage: Upon receipt, briefly centrifuge the vial and store at –80 °C for long-term preservation. Avoid repeated freeze–thaw cycles, which can cause protein aggregation and loss of activity. Aliquot the protein into single-use volumes before freezing.
• Reconstitution: If supplied in lyophilized form, reconstitute in the recommended buffer (typically phosphate-buffered saline, pH 7.4, supplemented with a carrier protein such as 0.1% BSA) according to the product datasheet. Allow the solution to equilibrate at room temperature before use.
• Working conditions: Keep reconstituted protein on ice during experimental setup to minimize degradation. Use low-binding tubes to reduce adsorption losses.
• Quality assurance: Aladdin Scientific performs SDS-PAGE and/or Western blot analysis to confirm molecular weight and purity. Endotoxin levels are tested by LAL assay. Detailed lot-specific certificates of analysis (CoA) are available on request.

Please consult the product-specific datasheet for exact buffer composition, concentration, purity grade, and recommended working concentrations, as these may vary by lot.

Ordering Information and Support

Recombinant Human GRAMD1C Protein is available from Aladdin Scientific under SKU rp369104. This product is intended for research use only and is not approved for diagnostic, therapeutic, or veterinary applications.

For custom quantities, bulk pricing, or specific formulation requirements, please contact our technical sales team. Our scientific support specialists are available to assist with application optimization, protocol recommendations, and experimental design.

To ensure product authenticity and lot traceability, always order directly through official Aladdin Scientific channels or authorized distributors. Certificate of Analysis (CoA) and Safety Data Sheet (SDS) documents are available upon request or downloadable from the product page.