Mannose receptor

mannose receptor, C type 1
Identifiers
Symbol	MRC1
Alt. symbols	CD206
Entrez	4360
HUGO	7228
OMIM	153618
RefSeq	NM_002438
UniProt	P22897
Other data
Locus	Chr. 10 p13

mannose receptor, C type 2
Identifiers
Symbol	MRC2
Alt. symbols	CD280
Entrez	9902
HUGO	16875
RefSeq	NM_006039
UniProt	Q9UBG0
Other data
Locus	Chr. 17 q23

The mannose receptor is a C-type lectin carbohydrate binding protein primarily present on the surface of macrophages and dendritic cells. It helps recognize pathogens that have mannose on their surface, and triggers one pathway of the complement system.

The function of this receptor is to recognize complex carbohydrates that are located on glycoproteins that are a part of many different biological processes. Some of those processes include cell–cell recognition, serum glycoprotein turnover, and neutralization of pathogens.^[1] The protein also functions as a type 1 membrane immune receptor that mediates the endocytosis of gycoproteins by macrophages.^[1] The structure of these proteins allows it to bind to high mannose structures on the surface of potentially pathogenic viruses, bacteria, and fungi so that they can be engulfed by the cell.^[1]

Mannose receptors have been researched as a target for vaccines.^[2]

Types

Humans express two types of mannose receptors, each encoded by its own gene:

Gene	Protein	Aliases
MRC1	Macrophage mannose receptor 1	C-type mannose receptor 1, C-type lectin domain family 13 member D (CLEC13D), CD206, MMR
MRC2	Macrophage mannose receptor 2	C-type mannose receptor 2, Urokinase-type plasminogen activator receptor-associated protein, CD280

The MRC1 gene is in close proximity to MRC1L1 and has a gene loci that includes the gene, MRC1L1, as well as LOC340843 and LOC340893.^[1] The gene also consist of nearly two identical regions, some think that they are duplicated regions.^[1] Recombinant proteins produced in yeast may be subject to increased addition of mannose, in patterns different from those of a human cell.^[3] Dendritic cells of the immune system possess a mannose receptor that enables them to take up mannosylated proteins, and utilize fragments of them for antigen presentation.^[4]

Function

The macrophage mannose receptor also interacts with HIV proteins. These interactions affect the gp120 and its ability to bind to the B cells through MRC1 receptors and an increase production of matrix mannose receptors.^[1] The protein, Nef interacts with MRC1 by down regulating the receptors on the surface of macrophages and dendritic cells. The tat protein represses the transcription of MRC1 promoters by down regulating the expression of MRC1.^[1] All of these proteins interact with MRC1 so that the virus can continue to spread and more research is being conducted trying to understand how stop these interactions from occurring.

More is going to be understood of this gene as more research is done looking at using it to fight tumor growth and HIV.

See also

• mannose

References

1. ^ ^{a b c d e f g} "MRC1 mannose receptor, C type 1 [Homo sapiens"]. Entrez Gene. National Center for Biotechnology Information. http://www.ncbi.nlm.nih.gov/gene/4360. 
2. ^ Keler T, Ramakrishna V, Fanger M (2004). "Mannose receptor-targeted vaccines". Expert Opin Biol Ther 4 (12): 1953–62. doi:10.1517/14712598.4.12.1953. PMID 15571457. 
3. ^ Vlahopoulos S, Gritzapis AD, Perez SA, Cacoullos N, Papamichail M, Baxevanis CN (July 2009). "Mannose addition by yeast Pichia Pastoris on recombinant HER-2 protein inhibits recognition by the monoclonal antibody herceptin". Vaccine 27 (34): 4704–8. doi:10.1016/j.vaccine.2009.05.063. PMID 19520203. 
4. ^ Shimizu K, Fujii S (2008). "An adjuvant role of in situ dendritic cells (DCs) in linking innate and adaptive immunity". Front. Biosci. 13: 6193–201. PMID 18508653. http://www.bioscience.org/2008/v13/af/3147/fulltext.htm. 

External links

• MeSH mannose+receptor
• http://users.path.ox.ac.uk/~cholt/sgMMR.html