MASP-3 and its association with distinct complexes of the mannan-binding lectin complement activation pathway

Immunity. 2001 Jul;15(1):127-35. doi: 10.1016/s1074-7613(01)00161-3.


The mannan-binding lectin (MBL) pathway of complement activation is part of the innate immune defense. The binding of MBL to microbial carbohydrates activates the MBL-associated serine proteases (MASPs), which recruit the complement factors, C4 and C2, to generate the C3 convertase or directly activate C3. We present a phylogenetically highly conserved member of the MBL complex, MASP-3, which is generated through alternative splicing of the MASP-1/3 gene. The designation of MASP-3 as a protease is based on homology to known MASPs. Different MBL oligomers were found to have distinct MASP composition and biological activities. MASP-1, MAp19, and direct C3-cleaving activity are associated with smaller oligomers whereas MASP-3 is found together with MASP-2 on larger oligomers. MASP-3 downregulate the C4 and C2 cleaving activity of MASP-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing
  • Amino Acid Sequence
  • Carrier Proteins / metabolism*
  • Cloning, Molecular
  • Collectins
  • Complement Activation*
  • Humans
  • Mannose-Binding Protein-Associated Serine Proteases
  • Molecular Sequence Data
  • Serine Endopeptidases / chemistry
  • Serine Endopeptidases / genetics
  • Serine Endopeptidases / metabolism
  • Serine Endopeptidases / physiology*


  • Carrier Proteins
  • Collectins
  • Mannose-Binding Protein-Associated Serine Proteases
  • Serine Endopeptidases

Associated data

  • GENBANK/AF284421