Recombinant Human GLTP Protein: Function & Research Use

Recombinant Human GLTP Protein is a bacterially or eukaryotically expressed form of the human glycolipid transfer protein, enabling researchers to study intermembrane glycolipid transport, lipid-binding mechanisms, and related metabolic pathways in well-controlled in vitro settings.

Protein Name

Glycolipid Transfer Protein (GLTP)

Species

Human (Homo sapiens)

Primary Function

Facilitates intermembrane transfer of glycolipids, particularly glycosphingolipids

Protein Format

Recombinant, typically lyophilized or supplied in carrier buffer

Key Research Areas

Lipid metabolism, membrane biology, sphingolipid signaling, cancer biology

Catalog SKU

rp369558

What Is GLTP? Biology and Molecular Function

Glycolipid Transfer Protein (GLTP) is a small, soluble cytosolic protein that belongs to the GLTP superfamily, characterized by a unique two-layer α-helical sandwich fold distinct from other lipid-binding protein families. GLTP specifically recognizes and transfers glycolipids—most notably glycosphingolipids (GSLs)—between membrane bilayers in a non-vesicular manner.

In cells, GLTP is thought to play a critical role in maintaining glycolipid homeostasis, particularly at the trans-Golgi network and endosomal compartments. Its lipid-binding pocket accommodates the ceramide backbone of glycosphingolipids, while polar interactions with the sugar headgroup confer selectivity. This selectivity makes GLTP an invaluable molecular tool for dissecting glycolipid biology in vitro.

Beyond its housekeeping role in lipid transport, GLTP has been implicated in the regulation of sphingolipid-mediated signaling cascades. Changes in GLTP expression have been linked to altered ceramide and sphingosine-1-phosphate (S1P) levels, influencing cell proliferation, apoptosis, and differentiation.

Biochemical Properties of Recombinant Human GLTP

Recombinant Human GLTP is produced using standard recombinant protein expression systems, yielding a well-characterized protein suitable for a wide range of biochemical assays. The mature human GLTP protein has a molecular weight of approximately 24 kDa and functions as a monomer under physiological conditions.

Key biochemical characteristics include:

• Lipid Binding Specificity: GLTP exhibits preferential binding to glycolipids bearing one or more sugar moieties, including galactosylceramide (GalCer), glucosylceramide (GlcCer), and more complex GSLs. It does not efficiently transfer phospholipids or cholesterol.
• Transfer Mechanism: GLTP mediates lipid transfer through a direct contact or collision-based mechanism between donor and acceptor membranes, independent of ATP or other energy cofactors.
• pH and Temperature Stability: The protein is generally active across a physiological pH range (pH 6.5–8.0) and is stable at 4°C for short-term storage; long-term storage is recommended at −20°C or −80°C.

Researchers should reconstitute lyophilized GLTP protein in the recommended buffer (typically phosphate-buffered saline with carrier protein) and avoid repeated freeze-thaw cycles to preserve activity.

Research Applications of Recombinant Human GLTP

Recombinant Human GLTP Protein is employed across a diverse range of experimental contexts in cell biology, biochemistry, and disease-related research:

1. In Vitro Lipid Transfer Assays: GLTP is widely used to measure the kinetics of glycolipid transfer between liposomal membranes, providing quantitative data on transfer rates and substrate specificity.
2. Structural and Biophysical Studies: The protein serves as a model system for studying protein-lipid interactions using techniques such as X-ray crystallography, NMR spectroscopy, and surface plasmon resonance (SPR).
3. Glycosphingolipid Metabolism Research: GLTP is used to probe the non-vesicular lipid trafficking pathway, complementing vesicle-based transport studies and helping delineate the relative contribution of each pathway.
4. Cancer and Disease Biology: Altered GLTP expression has been observed in certain cancers; recombinant protein is used in cell-free systems to study how GLTP modulates sphingolipid rheostat components (ceramide, S1P) relevant to tumor biology.
5. Enzyme and Binding Kinetics: Fluorescence-based assays using pyrene-labeled or BODIPY-labeled glycolipids allow precise measurement of GLTP-mediated transfer kinetics and binding affinities.

These applications collectively make Recombinant Human GLTP an essential reagent for lipid biology laboratories.

Handling, Storage, and Quality Considerations

Proper handling of Recombinant Human GLTP Protein is essential to maintain biological activity and experimental reproducibility:

• Reconstitution: Lyophilized protein should be reconstituted with sterile, ultra-pure water or the supplier-recommended buffer. Allow the vial to equilibrate to room temperature before opening.
• Storage: Aliquot reconstituted protein to minimize freeze-thaw cycles. Store aliquots at −20°C for up to several months, or at −80°C for longer-term storage. Avoid storage in frost-free freezers.
• Carrier Protein: Adding bovine serum albumin (BSA, 0.1%) to the storage buffer is recommended to stabilize dilute protein solutions and prevent adsorption to tube surfaces.
• Purity and Activity Verification: Confirm protein purity by SDS-PAGE before use. Functional activity may be verified using a standard fluorescent lipid transfer assay. Aladdin Scientific's recombinant proteins are manufactured under quality-controlled conditions to ensure batch-to-batch consistency.
• Safety: Handle as a general laboratory chemical. Refer to the product-specific Safety Data Sheet (SDS) for disposal and handling information.

Frequently asked questions

What is the biological function of human GLTP?

Human GLTP (Glycolipid Transfer Protein) is a cytosolic protein that facilitates the non-vesicular, intermembrane transfer of glycolipids—especially glycosphingolipids—between cellular membranes. It plays a role in maintaining glycolipid homeostasis and has been linked to sphingolipid-mediated signaling pathways that regulate cell proliferation and apoptosis.

What types of lipids does GLTP transfer, and are there any it does not transfer?

GLTP specifically transfers glycolipids containing one or more sugar residues, such as galactosylceramide (GalCer) and glucosylceramide (GlcCer). It does not efficiently transfer non-glycosylated lipids such as phosphatidylcholine, phosphatidylethanolamine, or cholesterol, making it a highly selective lipid transfer tool.

How should I reconstitute and store Recombinant Human GLTP Protein to maintain activity?

Reconstitute lyophilized GLTP in sterile, ultra-pure water or the supplier-recommended buffer, and allow the vial to reach room temperature before opening. Aliquot the reconstituted protein to avoid repeated freeze-thaw cycles, and store aliquots at −20°C for short-to-medium term or −80°C for long-term use. Adding 0.1% BSA as a carrier is recommended for dilute solutions.

What assays are commonly used to measure GLTP lipid transfer activity?

The most common approach uses fluorescently labeled glycolipids—such as pyrene-labeled or BODIPY-labeled galactosylceramide—incorporated into donor liposomes. Transfer of labeled lipid to acceptor liposomes is monitored by changes in fluorescence intensity or resonance energy transfer (FRET), allowing calculation of transfer rates and kinetic parameters.

Is Recombinant Human GLTP suitable for use in cell-based studies?

Recombinant Human GLTP is primarily designed for in vitro biochemical and biophysical assays. While it can in principle be introduced into cell-based systems using transfection or protein delivery methods, its most validated applications are in cell-free lipid transfer assays and structural studies. For cell-based overexpression studies, a plasmid or viral expression construct encoding GLTP may be more appropriate.

References

1. Mattjus P. Glycolipid transfer proteins and membrane interaction. Biochim Biophys Acta. 2009;1788(1):267-272.
2. Brown RE, Mattjus P. Glycolipid transfer proteins. Biochim Biophys Acta. 2007;1771(6):746-760.
3. Airenne TT, et al. Structure of human glycolipid transfer protein: defining molecular determinants of glycolipid transfer activity and hepatitis C virus NS5B inhibition. Biochemistry. 2006;45(17):5628-5638.

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