3kqg
From Proteopedia
Trimeric Structure of Langerin
Structural highlights
DiseaseCLC4K_HUMAN Defects in CD207 are the cause of Birbeck granule deficiency (BIRGD) [MIM:613393. It is a condition characterized by the absence of Birbeck granules in epidermal Langerhans cells. Despite the lack of Birbeck granules Langerhans cells are present in normal numbers and have normal morphologic characteristics and antigen-presenting capacity.[1] [2] FunctionCLC4K_HUMAN Calcium-dependent lectin displaying mannose-binding specificity. Induces the formation of Birbeck granules (BGs); is a potent regulator of membrane superimposition and zippering. Binds to sulfated as well as mannosylated glycans, keratan sulfate (KS) and beta-glucans. Facilitates uptake of antigens and is involved in the routing and/or processing of antigen for presentation to T cells. Major receptor on primary Langerhans cells for Candida species, Saccharomyces species, and Malassezia furfur. Protects against human immunodeficiency virus-1 (HIV-1) infection. Binds to high-mannose structures present on the envelope glycoprotein which is followed by subsequent targeting of the virus to the Birbeck granules leading to its rapid degradation.[3] [4] [5] [6] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedLangerin, an endocytic receptor of Langerhans cells, binds pathogens such as human immunodeficiency virus by recognition of surface glycoconjugates and mediates their internalization into Birbeck granules. Langerin has an extracellular region consisting of a C-type carbohydrate-recognition domain (CRD) and a neck region that stabilizes formation of trimers. As in many other C-type lectins, oligomerization is required for high affinity binding to glycan ligands and is also likely to be important for determining specificity. To facilitate structural analysis of the human langerin trimer, a truncated form of the extracellular region, consisting of part of the neck and the CRD, has been characterized. Like the full-length protein, truncated langerin exists as a stable trimer in solution. Glycan array screening with the trimeric fragment shows that high mannose oligosaccharides are the best ligands for langerin. Structural analysis of the trimeric fragment of langerin confirms that the neck region forms a coiled-coil of alpha-helices. Multiple interactions between the neck region and the CRDs make the trimer a rigid unit with the three CRDs in fixed positions and the primary sugar-binding sites separated by a distance of 42 A. The fixed orientation of the sugar-binding sites in the trimer is likely to place constraints on the ligands that can be bound by langerin. Trimeric structure of langerin.,Feinberg H, Powlesland AS, Taylor ME, Weis WI J Biol Chem. 2010 Apr 23;285(17):13285-93. Epub 2010 Feb 24. PMID:20181944[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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