1tl2
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(New page: 200px<br /><applet load="1tl2" size="450" color="white" frame="true" align="right" spinBox="true" caption="1tl2, resolution 2.0Å" /> '''TACHYLECTIN-2 FROM TA...)
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Revision as of 01:14, 21 November 2007
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TACHYLECTIN-2 FROM TACHYPLEUS TRIDENTATUS (JAPANESE HORSESHOE CRAB)
Overview
Tachylectin-2, isolated from large granules of the hemocytes of the, Japanese horseshoe crab (Tachypleus tridentatus), is a 236 amino acid, protein belonging to the lectins. It binds specifically to, N-acetylglucosamine and N-acetylgalactosamine and is a part of the innate, immunity host defense system of the horseshoe crab. The X-ray structure of, tachylectin-2 was solved at 2.0 A resolution by the multiple isomorphous, replacement method and this molecular model was employed to solve the, X-ray structure of the complex with N-acetylglucosamine. Tachylectin-2 is, the first protein displaying a five-bladed beta-propeller structure. Five, four-stranded antiparallel beta-sheets of W-like topology are arranged, around a central water-filled tunnel, with the water molecules arranged as, a pentagonal dodecahedron. Tachylectin-2 exhibits five virtually identical, binding sites, one in each beta-sheet. The binding sites are located, between adjacent beta-sheets and are made by a large loop between the, outermost strands of the beta-sheets and the connecting segment from the, previous beta-sheet. The high number of five binding sites within the, single polypeptide chain strongly suggests the recognition of carbohydrate, surface structures of pathogens with a fairly high ligand density. Thus, tachylectin-2 employs strict specificity for certain N-acetyl sugars as, well as the surface ligand density for self/non-self recognition.
About this Structure
1TL2 is a Single protein structure of sequence from Tachypleus tridentatus with NDG as ligand. Full crystallographic information is available from OCA.
Reference
Tachylectin-2: crystal structure of a specific GlcNAc/GalNAc-binding lectin involved in the innate immunity host defense of the Japanese horseshoe crab Tachypleus tridentatus., Beisel HG, Kawabata S, Iwanaga S, Huber R, Bode W, EMBO J. 1999 May 4;18(9):2313-22. PMID:10228146
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