PMID- 9920905
OWN - NLM
STAT- MEDLINE
DCOM- 19990226
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 6
DP  - 1999 Feb 5
TI  - Molecular determinants of oligomer formation and complement fixation in 
      mannose-binding proteins.
PG  - 3580-9
AB  - Rat serum mannose-binding protein (MBP-A) functions as part of the innate immune 
      system by targetting complement toward potentially pathogenic microorganisms. In 
      order to examine the molecular basis for complement activation, rat MBP-A has 
      been overproduced in Chinese hamster ovary cells. Recombinant protein is 
      post-translationally modified in the same way as the native lectin. Hydrodynamic 
      studies indicate that MBP-A consists predominantly of covalent oligomers 
      containing one to four copies of a subunit that comprises a trimer of 
      polypeptides. These oligomers are non-interconverting and do not assemble into 
      higher order structures at concentrations in excess of those normally found in 
      serum. Disulfide bonds formed between cysteine residues at the N-terminal end of 
      the collagen-like domain link polypeptides to form covalent oligomers. Analysis 
      of wild-type MBP-A and MBP-A containing the substitution Cys6 --> Ser suggests 
      that polypeptides within each trimeric structural unit are mostly linked by 
      disulfide bonds between cysteine residues at positions 13 and 18 arranged in an 
      asymmetrical configuration. Disulfide bonds involving Cys6 connect polypeptides 
      within separate trimers. Analysis of chimeras between MBP-A and rat liver MBP 
      (MBP-C) indicates that residues within the N-terminal region of the collagenous 
      domain and the cysteine-rich domain of MBP-A enable assembly of trimers into 
      higher order oligomers. The activity of MBP-A in a hemolytic complement fixation 
      assay using mannan-coated sheep erythrocytes was approximately 20-fold greater 
      than the activity of MBP-C. Analysis of the MBP chimeras and isolated oligomers 
      of MBP-A reveals that the larger oligomers are more efficient at complement 
      activation. These data indicate that the overall complement fixing activity of 
      MBP-A is a function of the individual molecular activities of oligomers and their 
      relative abundance within the serum.
FAU - Wallis, R
AU  - Wallis R
AD  - Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford 
      OX1 3QU, United Kingdom.
FAU - Drickamer, K
AU  - Drickamer K
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Biopolymers)
RN  - 0 (Carrier Proteins)
RN  - 0 (Mannose-Binding Lectins)
RN  - 0 (Recombinant Proteins)
RN  - 9007-36-7 (Complement System Proteins)
RN  - PHA4727WTP (Mannose)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Biopolymers
MH  - CHO Cells
MH  - Carrier Proteins/chemistry/*metabolism
MH  - Complement Activation
MH  - Complement System Proteins/*metabolism
MH  - Cricetinae
MH  - Mannose/*metabolism
MH  - Mannose-Binding Lectins
MH  - Molecular Sequence Data
MH  - Protein Processing, Post-Translational
MH  - Rats
MH  - Recombinant Proteins/chemistry/metabolism
MH  - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
EDAT- 1999/01/28 00:00
MHDA- 1999/01/28 00:01
CRDT- 1999/01/28 00:00
PHST- 1999/01/28 00:00 [pubmed]
PHST- 1999/01/28 00:01 [medline]
PHST- 1999/01/28 00:00 [entrez]
AID - S0021-9258(19)87982-6 [pii]
AID - 10.1074/jbc.274.6.3580 [doi]
PST - ppublish
SO  - J Biol Chem. 1999 Feb 5;274(6):3580-9. doi: 10.1074/jbc.274.6.3580.