1. CD 206: MANNOSE RECEPTOR
CATEGORY: RECEPTORS & MOLECULES
CD 206: Mannose Receptor
Luisa Martinez-Pomares, University of Nottingham, UK
The mannose receptor is a member of the c-type lectin family of receptors. It is expressed by macrophages, dendritic cells and hepatic and lymphatic endothelia. Expression in macrophages and dendritic cells is regulated by microbial products and cytokines. The mannose receptor is an endocytic receptor; it constantly recycles between the plasma membrane and the early endocytic compartment. Because of its ability to recognise molecules of endogenous and microbial origin it is thought to have a major role in homeostasis and immunity.
Domain structure of the mannose receptor:
CR: Cysteine-rich domain
Recognises sulphated
carbohydrates terminated in
SO4-(3)-Gal- or SO4-(3/4)-GalNAc-.
Binding to ligands improved
by protein multimerisation.
FNII: Fibronectin type II domain
Recognises native and denatured collagens.
Binds Collagen I, II, III, IV and (weakly) V..
Requires protein multimerisation for binding. CR
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FNII
CTLD: C-type lectin-like domain
Through these domains MR binds
complex carbohydrates terminated in
mannose, fucose or N-acetyl-glucosamine.
Cytoplasmic tail
Intracellular targeting mediated by a tyrosine-based motif in the cytoplasmic tail, similar to the one found in the low density lipoprotein (LDL)-receptor (FENTLY).
CTLD
CTLD-4: Is a C-type lectin carbohydrate recognition domain. The only CTLD able to bind carbohydrate in isolation.
Requires Ca2+ and neutral pH.
Recycling from early endosomes is mediated
by the di-aromatic motif comprised of the
tyrosine present in the endocytosis motif and
an adjacent phenylalanine.
Mannose receptor ligands:
Sulphated
glycoprotein hormones from
anterior pituitary.
Chondroitin sulphate.
Sulphated Lewisx/a.
SorLA/LR11 in mouse kidney.
CD45 and sialoadhesin in
mouse secondary lymphoid organs.
CR doman ligands
FNII domain ligands
CTLD ligands
Microbial:
Mycobacterium tuberculosis
HIV
Candida albicans
Pneumocystis carinii
Klebsiella pneumoniae LPS
Streptococcus pneumoniae CPS
Dengue virus
Collagens
Endogenous:
Lysosomal hydrolases
Myeloperoxidase
Tissue plasminogen activator
Thyroglobulin
Ligands in secretory organs