CD207 LANGERIN (langerhans cell specific C type lectin),
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 2 glycoprotein
Dendritic Cell
Langerhans Cell
40 / 40

Expression
CD207 is expressed on a subset of dendritic cells, immature dendritic cells of the epidermis and mucosa and is found on a subset of cultured blood CD11c+ dendritic cells and TGFb differentiated monocyte derived dendritic cells.  The protein encoded by this gene is expressed in immature Langerhans cells and the level decreases during maturation.  It is localized in the Birbeck granules, organelles present in the cytoplasm of Langerhans cells and consisting of superimposed and zippered membranes.  CD207 is downregulated following activation through CD40.  Some expression may occur in the dermis, in T cell areas but there is no expression within germinal centers.

Structure
MOLECULAR FAMILY NAME: Belongs to the C-type lectin superfamily.

CD207 is a single-pass type-2 328 aa glycoprotein.  It contains an extracellular domain containing a calcium dependent  C-type lectin domain featuring an EPN motif with mannose-type specificity and 2 N-glycosylation sites in the membrane-proximal neck domain, a transmembrane domain and a 43 aa intracellular cytoplasmic domain with a proline-rich potential signal transduction motif (WPREPPP) which is predicted to be a signal transduction site that associates with SH3 domain proteins involved in vesicular trafficking and cytosketal movement.  The human CD207 has a single Ca2+ dependent carbohydrate recognition (CRD) in the extracellular portion.  The mouse CD207 displays conservation in all features of the human molecule.  cDNA encoding human and mouse CD207 were isolated and displayed 66% overall homology.  CD207 provides a new reagent for characterized Langerhans histiocytosis.  The molecule was identified by reactivity with mAb DCGM-4 which recognizes an extracellular epitope present on Langerhans type cells.  Langerin was cloned from a dendritic cell library using the mAb to select for expression.

MOLECULAR MASS
Cell Type Unreduced Reduced
40 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION

There are 2 potential N-glycosylation sites at positions 87-89 and 180-182.  Both human and murine CD207 genes contain 6 exons, 3 of which encode the CRD as described for a number of type 2 lectins.


Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD207

CD207 binds mannose-bearing glycoproteins and glycolipids found on microbial pathogens, including the gp20 protein of HIV.

Function
CD207 is a specific marker for Langerhans cells and is an endocytic receptor with a functional C-type lectin domain with mannose specificity.  High level expression of CD207 induces membrane superimposition and zippering which form pentilaminar organelles known as Birbeck granules (BG).  It has been proposed that the calcium-dependent lectin displays mannose-binding specificity and induces the internalization of antigen into the formation of Birbeck granules.  CD207 molecules are an integral part of BGs.  The mildly acidic content suggests a role in a non-classical antigen processing and endocytic pathway. 
Ligand binding results in rapid internalization of CD207.  However while CD207 functions as an endocytic receptor and unlike the mannose receptor CD206, there is no evidence that CD207 is part of the classic antigen-processing pathway because it does not route into the MHC class II molecules.  CD207 is a specific marker for Langerhans cells.  In vitro studies of Langerhans cells have demonstrated that mycobacterial antigen lipoarabinomannan is interalized in association with CD207 but is then loaded onto CD1a and presented to T cells.   As transfection of human CD207 cDNA into fibroblasts results in the formation of the granules, engagement of the cell surface langerin on Langerhans cells is likely to direct antigen into a non-conventional pathway via induction of these organelles by superimposition of the cytomembrane.  There is only one case of a deficient patient with Langerhans cells lacking BG.  Also null mice are phenotypically identical to wild-type mice.  Langerhans cells from CD207-/- mice lack BG but can presnt antigen to CD4+ and CD8+ T cells.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD207 IN INTACT ANIMAL: No information.


Comments
MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD207: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD207: No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene50489Q9UJ71
Antibodies

Revised June 25, 2008


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