2J64: H-Ficolin

Citation:
Abstract
Innate immunity relies critically upon the ability of a few pattern recognition molecules to sense molecular markers on pathogens, but little is known about these interactions at the atomic level. Human L- and H-ficolins are soluble oligomeric defence proteins with lectin-like activity, assembled from collagen fibers prolonged by fibrinogen-like recognition domains. The X-ray structures of their trimeric recognition domains, alone and in complex with various ligands, have been solved to resolutions up to 1.95 and 1.7 A, respectively. Both domains have three-lobed structures with clefts separating the distal parts of the protomers. Ca(2+) ions are found at sites homologous to those described for tachylectin 5A (TL5A), an invertebrate lectin. Outer binding sites (S1) homologous to the GlcNAc-binding pocket of TL5A are present in the ficolins but show different structures and specificities. In L-ficolin, three additional binding sites (S2-S4) surround the cleft. Together, they define an unpredicted continuous recognition surface able to sense various acetylated and neutral carbohydrate markers in the context of extended polysaccharides such as 1,3-beta-D-glucan, as found on microbial or apoptotic surfaces.
PDB ID: 2J64Download
MMDB ID: 43980
PDB Deposition Date: 2006/9/25
Updated in MMDB: 2012/10
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 2J64: trimeric; determined by author and by software (PQS)
Molecular Components in 2J64
Label Count Molecule
Proteins (3 molecules)
3
Ficolin-3(Gene symbol: FCN3)
Molecule annotation
Chemicals (3 molecules)
1
3
* Click molecule labels to explore molecular sequence information.

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