Send to

Choose Destination
See comment in PubMed Commons below
Biosci Rep. 1999 Aug;19(4):283-92.

Lectin-carbohydrate interactions: fine specificity difference between two mannose-binding proteins.

Author information

  • 1Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.


Two types of rat mannose-binding proteins (MBPs), MBP-A (serum type) and MBP-C (liver type), have similar binding specificity for monosaccharide and similar binding site construct according to the X-ray structure, but exhibit different affinity toward natural oligosaccharides and glycoproteins. To understand the basis for this phenomenon, we used cloned fragment of MBP-A and -C (entire carbohydrate-recognition domain and a short connecting piece) that exists as stable trimers in various binding studies. Binding of a number of mannose-containing di- and tri-saccharides and high-mannose type oligosaccharides indicated that MBP-C has an extended binding area of weak interaction with the second and the third mannose residues, whereas MBP-A recognizes just a single mannose residue. In addition, MBP-C has a weak secondary binding site some 25 A away from the primary site. These findings explain the higher affinity of MBP-C for natural high-mannose type oligosaccharides as compared to MBP-A. A huge affinity differential manifested by natural glycoproteins (e.g., inhibitory potency of thyroglobulin is approximately 200 fold higher for MBP-C than for MBP-A in a solid-phase assay) may be due to steric hindrance experienced by MBP-A in the competition assay, and suggests different arrangement of subunit in the MBP trimers.

[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk