Isolation and characterization of mannan-binding proteins from chicken liver.
Two binding proteins which recognize and bind mannose and N-acetylglucosamine (mannan-binding proteins, MBP) have been isolated from chicken liver to near homogeneity mainly by affinity chromatography on a column of Sepharose 4B-mannan. The neutral binding protein (pI 7.0), which has a high glycine content, is an analog of mammalian liver MBP (F-I). F-I consists of a series of proteins composed of two subunits of 28,000 (A) and 32,000 (B) Da. The proteins have molecular weights ranging from 280,000 to 740,000 and subunit compositions ranging from 6A + 4B to 5A + 19B. With increasing molecular weight the specific activity of mannan binding increases gradually, accompanied by a slight change in specificity to a preference for mannose rather than N-acetylglucosamine. The acidic binding protein (pI 5.1) is a glycoprotein with a high glutamic acid content (F-II). The molecular weight of F-II was estimated to be 640,000, and it is composed of single subunits of 41,000 Da. The two MBPs isolated in this study are distinct from the liver lectin specific for N-acetylglucosamine-terminated glycoproteins isolated from the same source [T. Kawasaki and G. Ashwell (1977) J. Biol. Chem. 252, 6536-6543] in chemical properties and binding specificities.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000378:metabolism; D037222:Collectins; D007700:Kinetics; D037102:Lectins / Q000302:isolation & purification* / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D046911:Macromolecular Substances; D008351:Mannans / Q000378:metabolism*; D008970:Molecular Weight
D000596:Amino Acids; D002352:Carrier Proteins; D037222:Collectins; D037102:Lectins; D046911:Macromolecular Substances; D008351:Mannans