title: X-ray crystal structure of a galactose-specific C-type lectin possessing a novel decameric quaternary structure.
abstract: Rattlesnake venom lectin (RSL) from the western diamondback rattlesnake (Crotalus atrox) is an oligomeric galactose-specific C-type lectin. The X-ray crystal structure of RSL, in complex with lactose and thiodigalactoside, at 2.2 and 2.3 A resolution, respectively, reveals a decameric protein composed of two 5-fold symmetric pentamers arranged in a staggered, back-to-back orientation. Each monomer corresponds to a single canonical C-type lectin carbohydrate recognition domain devoid of accessory domains and is disulfide-bonded to a monomer in the other pentamer. The structure is the first example of that of a carbohydrate complex of a vertebrate galactose-specific C-type lectin. The 10 carbohydrate-binding sites, located on the rim of the decamer, suggest a role for multivalent interactions and a mechanism for RSL's ability to promote receptor cross-linking and cell aggregation.
authors.affiliation: Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
authors.forename: John R
authors.initials: JR
authors.lastname: Walker
authors.forename: Bhushan
authors.initials: B
authors.lastname: Nagar
authors.forename: N Martin
authors.initials: NM
authors.lastname: Young
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hirama
authors.forename: James M
authors.initials: JM
authors.lastname: Rini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D003435:Crotalid Venoms / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry; D005690:Galactose / Q000737:chemistry*; D007785:Lactose / Q000737:chemistry; D037181:Lectins, C-Type / Q000737:chemistry*; D008969:Molecular Sequence Data; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D013862:Thiogalactosides / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D003435:Crotalid Venoms; D004220:Disulfides; D037181:Lectins, C-Type; D013862:Thiogalactosides; C031803:thiodigalactoside; D007785:Lactose; D002118:Calcium; D005690:Galactose