Isolation and characterization of porcine mannan-binding proteins of different size and ultrastructure.
The authors report on the purification and characterization of mannan- binding proteins (MBP) isolated from porcine serum. The MBPs were purified by use of PEG precipitation, affinity chromatography on mannan-Sepharose, protein A- and anti-porcine IgM-Sepharose followed by gel filtration. The MBP proteins were collagenase sensitive and showed gamma 1-gamma 2-electrophoretic mobility. The MBP designated pMBP-28 had a molecular mass of 28 kDa when analysed on SDS-PAGE under reducing conditions and eluted corresponding to a molecular mass of approximately 700 kDa on gel filtration chromatography. Electron micrographs of pMBP-28 revealed an oligomeric protein similar to rodent MBP-A and human MBP but with a predominance of penta- and hexameric molecules. Another protein designated pMBP-27 was composed of peptides of 27 kDa and had an Mr of 300-350 kDa on gel filtration chromatography. Electron microscopy of pMBP-27 showed dimer and trimer molecules; the trimers without distinct stalk regions. The N-terminal 26(pMBP-27) and 24(MBP-28) amino acid residues showed 54% and 58% identity with human MBP.pMBP-28 showed a higher degree of sequence similarity to rat and mouse MBP-A (60% identity) than to mouse and rat MBP-C (41-45% identity). Both pMBPs exhibited Ca2+-dependent binding to D-mannose immobilized on agarose but no significant binding to N-acetyl-D-glucosamine- or fucose-agarose. The results further suggested the presence of a third pMBP which copurified with pMBP-27 but this protein was not sequenced.
Storgaard
P
P
Department of Medical Microbiology, Institute of Medical Biology, Odense University, Denmark.
Nielsen
E H
EH
Andersen
O
O
Skriver
E
E
Mortensen
H
H
Højrup
P
P
Leslie
G
G
Holmskow
U
U
Svehag
S E
SE
D000595:Amino Acid Sequence; D000818:Animals; D002236:Carbohydrate Conformation; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000648:ultrastructure; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D017364:Collagenases / Q000494:pharmacology; D037222:Collectins; D007123:Immunoelectrophoresis, Two-Dimensional; D037102:Lectins / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011485:Protein Binding / Q000276:immunology; D013552:Swine
D002352:Carrier Proteins; D037222:Collectins; D037102:Lectins; D008351:Mannans; D017364:Collagenases