Cd206

Acronym for Cluster of differentiation (CD) 206, CD206, also known as mannose receptor, is a transmembrane receptor protein (C-type lectin -s.u. lectins) that has an extracellular N-terminus and an intracellular C-terminus. CD206 is primarily expressed by macrophages and immature dendritic cells. CD206 is also expressed on human keratinocytes and dermal fibroblasts. CD206 is primarily synthesized as an inactive precursor. This precursor is proteolytically cleaved into its active form upon activation. This process takes place in the Golgi apparatus.

In fact, it is only a single receptor protein but, at least in animals, a receptor family with quite different functions. In humans, 2 receptor types are expressed, which are encoded by different genes:

Macrophage mannose receptor 1 (C-type mannose receptor 1 also MRC1; CD206). MRC1 gene coding on chromosome 10p13

Macrophage mannose receptor 2 (MRC2, CD280). MRC2 gene encoding chromosome 17q23.

The mannose receptor recognizes terminal mannose molecules, N-acetylglucosamines and fucose molecules. These are found on the surface of various microorganisms and thus play a role in natural or adaptive immunity.

Furthermore, the receptor acts as a kind of "clearing station" of circulating glycoproteins, including glycoprotein hormones. The expression of the mannose receptor constantly alternates between plasma membrane and cytosolic compartments.

The soluble and thus circulating mannose receptor consists of the complete extracellular part of the mannose receptor. It is involved in the transport of mannose-containing glycoproteins.

Removal of the receptor protein from macrophages leads to a reduced recognition of microbial pathogens such as those of Candida albicans, Aspergillus fumigatus, Pneumocystis carinii, and Leishmania donovani. This implies that the mannose receptor plays an important role as a "pathogen recognition receptor", as a recognition receptor and as a part of the natural and adaptive immune response to microbial pathogens.