SIGN R1 is a specific marker for the identification of macrophage subpopulations present in the marginal zone of spleen (the so-called marginal zone macrophages (MZM)), in the lymph node medulla, and in some strains, in the peritoneal cavity. MZM of the spleen are involved in the clearance of polysaccharides.
Mouse SIGN R1 is a C type lectin, like DC SIGN which is expressed on Human dendritic cells (DCs). However, Mmouse SIGN R1 itself is not expressed on DCs. SIGN R1 exists in an aggregated form, resistant to dissociation into monomers upon boiling in SDS under reducing conditions.
SIGN R1 mediates the uptake of encapsulated organisms and may be an important mediator for the uptake of microbes in both spleen and lymph node, particularly through the recognition of microbial polysaccharides.