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Jens Christian Jensenius

Purification and characterization of a bovine serum lectin (CL-43) with structural homology to conglutinin and SP-D and carbohydrate specificity similar to mannan-binding protein

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A previously undescribed bovine serum lectin (designated CL-43) was identified by its Ca(2+)-dependent binding to mannan and by its molecular mass of 43 kDa under reducing conditions on SDS-PAGE. The lectin was isolated by polyethylene glycol precipitation, affinity chromatography on mannan-Sepharose (followed by elution with EDTA), and absorption on Sepharose-4B-coupled rabbit anti-bovine Ig (to remove anti-mannan antibodies). Fractions containing the lectin were reapplied to mannan-Sepharose. Bound conglutinin was eluted with GlcNAc, and then the 43-kDa lectin, together with mannan-binding protein (MBP), was eluted with mannose. The 43-kDa lectin was separated from MBP by ion exchange chromatography on Mono-Q. On SDS-PAGE under nonreducing conditions the lectin showed a molecular mass of 120 kDa. On gel chromatography under nondissociating conditions the protein was eluted at a volume corresponding to a molecular mass of approximately 750 kDa. Amino acid analysis showed the presence of hydroxyproline and hydroxylysine and a high content of glycine (24.3%) indicating the presence of a collagen-like structure. This was supported by the susceptibility of the protein to collagenase digestion. The designation CL-43 was chosen since this molecule appears to belong to the collectins, i.e. proteins with collagen structure and lectin activity. The N-terminal sequence (27 amino acids) showed 56% identity with bovine SP-D and 44% identity to bovine conglutinin. An inhibition assay with biotinylated CL-43, using solid-phase mannan as ligand, revealed the following carbohydrate inhibition pattern: mannose and ManNAc > fucose > GlcNAc > glucose and maltose > galactose > lactose >> GalNAc. We conclude that CL-43 is a circulating lectin, with structural similarities to bovine conglutinin and SP-D, and a ligand binding profile resembling that of MBP.
Original languageEnglish
JournalJournal of Biological Chemistry
Pages (from-to)10120-5
Number of pages6
Publication statusPublished - 1993

    Research areas

  • Amino Acid Sequence, Animals, Blotting, Western, Carbohydrates, Carrier Proteins, Cattle, Chromatography, Affinity, Chromatography, Gel, Chromatography, Ion Exchange, Collectins, Electrophoresis, Polyacrylamide Gel, Glycoproteins, Humans, Lectins, Mannans, Molecular Sequence Data, Molecular Weight, Pulmonary Surfactant-Associated Protein D, Pulmonary Surfactants, Sequence Homology, Amino Acid, Serum Globulins

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