Recombinant Human MARCO Protein: Properties & Research Use

Recombinant Human MARCO Protein is a research-grade recombinant form of the macrophage receptor with collagenous structure, a class A scavenger receptor that plays essential roles in innate immune defense, pathogen recognition, and macrophage-mediated clearance of modified lipoproteins and microbial particles.

Protein Name

Macrophage Receptor with Collagenous Structure (MARCO)

SKU

rp366198

Protein Family

Class A Scavenger Receptor (SR-A) family

Primary Expression

Macrophages, dendritic cells, alveolar macrophages

Key Function

Pattern recognition, pathogen binding, modified lipoprotein uptake

Research Application

Innate immunity, host-pathogen interaction, atherosclerosis, lung biology

What Is MARCO? Gene, Structure, and Expression

MARCO (Macrophage Receptor with Collagenous Structure) is a type II transmembrane glycoprotein encoded by the MARCO gene located on human chromosome 2q14.2. It belongs to the class A scavenger receptor (SR-A) family, which also includes SR-AI and SR-AII. The extracellular region of MARCO comprises a short spacer domain, a collagenous domain, and a C-terminal scavenger receptor cysteine-rich (SRCR) domain — the latter being critical for ligand binding.

MARCO is constitutively expressed at high levels on subpopulations of tissue-resident macrophages, particularly alveolar macrophages in the lung and marginal zone macrophages in the spleen. Expression can be induced on monocyte-derived macrophages and dendritic cells upon inflammatory stimulation. Its restricted expression pattern makes MARCO a useful cell-type marker in immunological research.

Biological Functions of MARCO in Innate Immunity

MARCO functions as a pattern recognition receptor (PRR) capable of binding a broad range of polyanionic ligands, including bacterial lipopolysaccharide (LPS), lipoteichoic acid (LTA), CpG DNA, and unopsonized bacteria such as Staphylococcus aureus and Escherichia coli. This broad ligand-binding capacity allows MARCO to participate in the initial, antibody-independent clearance of bacterial pathogens.

Beyond microbial recognition, MARCO mediates the uptake of modified low-density lipoproteins (oxLDL) and environmental particles such as silica and polystyrene beads, implicating it in atherosclerosis pathogenesis and particle-induced lung injury. MARCO has also been shown to modulate downstream inflammatory signaling; receptor engagement can influence NF-κB activation and cytokine production in macrophages, underscoring its dual role in both physical clearance and immunomodulation.

Research Applications of Recombinant Human MARCO Protein

Recombinant Human MARCO Protein (rp366198) is a valuable reagent for a wide range of in vitro research applications. Key uses include:

• Binding and competition assays: Used to characterize ligand–receptor interactions, including binding kinetics and inhibitor screening targeting the SRCR domain.
• ELISA and immunoassay development: Serves as a standard or coating antigen for the development and validation of antibody-based detection systems.
• Cell-based functional studies: Added exogenously to investigate receptor-mediated endocytosis or used to generate stable cell lines for functional characterization.
• Drug discovery: Employed as a target protein in high-throughput screening campaigns aimed at identifying modulators of scavenger receptor activity relevant to infection, inflammation, and metabolic disease.
• Structural biology: Used in crystallography or cryo-EM studies to elucidate MARCO domain architecture and ligand-binding mechanisms.

Handling, Storage, and Quality Considerations

As with all recombinant proteins, proper handling and storage of Recombinant Human MARCO Protein are essential to maintain biological activity and experimental reproducibility. Researchers should observe the following general best practices:

• Storage: Aliquot upon receipt to avoid repeated freeze–thaw cycles, which can degrade protein integrity and reduce functional activity. Store according to the conditions specified on the product datasheet.
• Reconstitution: If lyophilized, reconstitute in the recommended buffer as described in the product protocol. Allow the vial to equilibrate to room temperature before opening.
• Carrier protein: When working at low concentrations, consider adding a carrier protein (e.g., BSA) to prevent adsorption to tube surfaces.
• Quality verification: Confirm protein purity and expected molecular weight by SDS-PAGE or Western blot before use in critical experiments. Endotoxin levels should be evaluated if the protein will be used in cell-based or in vivo assays.

Always consult the product-specific datasheet (absea#PP-11633) for lot-specific purity, activity, and storage recommendations.

Frequently asked questions

What is the MARCO protein and why is it important in immunology research?

MARCO (Macrophage Receptor with Collagenous Structure) is a class A scavenger receptor expressed primarily on tissue-resident macrophages. It recognizes and binds diverse pathogen-associated molecular patterns (PAMPs) and modified self-molecules, making it a key mediator of innate immune defense, pathogen clearance, and inflammatory regulation. Its involvement in infection, atherosclerosis, and lung disease makes it a broadly relevant research target.

What experimental formats is Recombinant Human MARCO Protein (rp366198) suitable for?

Recombinant Human MARCO Protein is suitable for a variety of in vitro assay formats, including ELISA development, ligand-binding and competition assays, immunoassay standardization, cell-based endocytosis studies, and drug discovery screening. It may also be used in structural studies such as protein crystallography or cryo-EM. Always verify suitability for your specific application by consulting the product datasheet.

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

To preserve activity, the protein should be aliquoted upon receipt to minimize freeze–thaw cycles. Store under the conditions specified in the product datasheet (absea#PP-11633). For dilute working solutions, adding a carrier protein such as BSA is recommended to prevent surface adsorption and loss of activity.

Is Recombinant Human MARCO Protein suitable for use in cell-based or in vivo assays?

Recombinant Human MARCO Protein may be applicable to cell-based studies; however, for such applications it is critical to verify endotoxin levels, as contaminating endotoxin can confound results, particularly in macrophage or immune cell assays. Consult the product datasheet for endotoxin specifications and confirm suitability for your specific cell or animal model system before use.

References

1. Elomaa O, et al. Cloning of a novel bacteria-binding receptor structurally related to scavenger receptors and expressed in a subset of macrophages. Cell. 1995;80(4):603–609.
2. Józefowski S, Kobzik L. MARCO and SR-AI mediate pulmonary clearance of unopsonized particles and bacteria via distinct mechanisms. J Immunol. 2004;173(8):5097–5106.
3. Mukhopadhyay S, Gordon S. The role of scavenger receptors in pathogen recognition and innate immunity. Immunobiology. 2004;209(1–2):39–49.

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