1gqm
From Proteopedia
The structure of S100A12 in a hexameric form and its proposed role in receptor signalling
Structural highlights
Function[S10AC_HUMAN] S100A12 is a calcium-, zinc- and copper-binding protein which plays a prominent role in the regulation of inflammatory processes and immune response. Its proinflammatory activity involves recruitment of leukocytes, promotion of cytokine and chemokine production, and regulation of leukocyte adhesion and migration. Acts as an alarmin or a danger associated molecular pattern (DAMP) molecule and stimulates innate immune cells via binding to receptor for advanced glycation endproducts (AGER). Binding to AGER activates the MAP-kinase and NF-kappa-B signaling pathways leading to production of proinflammatory cytokines and up-regulation of cell adhesion molecules ICAM1 and VCAM1. Acts as a monocyte and mast cell chemoattractant. Can stimulate mast cell degranulation and activation which generates chemokines, histamine and cytokines inducing further leukocyte recruitment to the sites of inflammation. Can inhibit the activity of matrix metalloproteinases; MMP2, MMP3 and MMP9 by chelating Zn(2+) from their active sites. Possesses filariacidal and filariastatic activity. Calcitermin possesses antifungal activity against C.albicans and is also active against E.coli and P.aeruginosa but not L.monocytogenes and S.aureus.[1] [2] [3] [4] 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 PubMedS100A12 is a member of the S100 subfamily of EF-hand calcium-binding proteins; it has been shown to be one of the ligands of the 'receptor for advanced glycation end products' (RAGE) that belongs to the immunoglobulin superfamily and is involved in diabetes, Alzheimer's disease, inflammation and tumour invasion. The structure of the dimeric form of native S100A12 from human granulocytes in the presence of calcium in space group R3 has previously been reported. Here, the structure of a second crystal form in space group P2(1) (unit-cell parameters a = 53.9, b = 100.5, c = 112.7A, beta = 94.6 degrees) solved at 2.7A resolution by molecular replacement using the R3 structure as a search model is reported. Like most S100 proteins, S100A12 is a dimer. However, in the P2(1) crystal form dimers of S100A12 are arranged in a spherical hexameric assembly with an external diameter of about 55 A stabilized by calcium ions bound between adjacent dimers. The putative target-binding sites of S100A12 are located at the outer surface of the hexamer, making it possible for the hexamer to bind several targets. It is proposed that the S100A12 hexameric assembly might interact with three extracellular domains of the receptor, bringing them together into large trimeric assemblies. The structure of S100A12 in a hexameric form and its proposed role in receptor signalling.,Moroz OV, Antson AA, Dodson EJ, Burrell HJ, Grist SJ, Lloyd RM, Maitland NJ, Dodson GG, Wilson KS, Lukanidin E, Bronstein IB Acta Crystallogr D Biol Crystallogr. 2002 Mar;58(Pt 3):407-13. Epub 2002, Feb 21. PMID:11856825[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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