MARCO MRCO (macrophage receptor with collagenous structure)
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 2 glycoprotein
Macrophage
Lymph Node
80 / 80
210 / 210

Expression
MARCO is expressed on macrophages in the marginal zone of the spleen and in the medullary cord of lymph nodes but not in the liver or lung.

Structure
MOLECULAR FAMILY NAME: Belong to the scavenger receptor cysteine-rich family.

MARCO is a single-pass homotrimeric type-2 520 aa glycoprotein.  It contains an extracellular domain which contains 1 270 aa collagen-like domain with glycine repeats, a 75 aa putative spacer domain with 2 potential N-linkled glycosylation sites and a cysteine-rich domain (SRCR) at the C terminus, a 25 aa transmembrane domain and a 49 aa N-terminal cytoplasmic sequence.  It is a member of the Group A scavenger receptor cysteine- rich (SRCR) superfamily.  It is expressed as a disulfide-linked trimer at the cell surface.  The mouse MARCO is a plasma membrane protein but the human MARCO polypeptide lacks the intracellular cysteine present in the mouse as well as two extracellular cysteines that form interchain disulfide bonds in the murine protein.  The predicted structure of MARCO is similar to scavenger receptor but differs in that MARCO has a longer collagenous domain where scavenger receptor has a coiled-coil region followed by a short collagen-like region.  The scavenger receptor domains of MARCO and scavenger receptor type 1 show a 49% aa sequence identity and each contain 6 cysteines.

MOLECULAR MASS
Cell Type Unreduced Reduced
210 kDa 80 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION

MARCO has 2 potential glycosylation sites.

Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH MARCO

COS cells expressing MARCO bind an acetylated low density lipoprotein and bacteria, specifically, E. coli and S. aureus.

Function

MARCO is a member of the scavenger receptor family and is part of the innate antimicrobial immune system.  It binds Gram-positive and Gram-negative bacteria via an extracellular, C-terminal scavenger receptor cystrine rich domain.  MARCO may form a trimeric molecule by the association of the collagenous domains of three identical polypeptide chains.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF MARCO IN INTACT ANIMAL: No information.



Comments
MOLECULAR INTERACTION-
PROTEINS ANDS DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF MARCO: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY MARCO: No information.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 8685Q9UEW3
MouseA55840U18424
Antibodies
PAL-1   View Reactivity

Revised June 25, 2008


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