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Characterization of the complex between mannose‐binding lectin trimer and mannose‐binding lectin‐associated serine proteases
Author(s) -
Tateishi Koichiro,
Kanemoto Takahiro,
Fujita Teizo,
Matsushita Misao
Publication year - 2011
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2011.00330.x
Subject(s) - mannan binding lectin , ficolin , lectin pathway , lectin , complement system , proteases , biology , masp1 , serine , c type lectin , biochemistry , mannose , trimer , innate immune system , complement component 2 , alternative complement pathway , chemistry , serine protease , dimer , immunology , receptor , antibody , enzyme , protease , organic chemistry
Mannose‐binding lectin (MBL) is an oligomeric serum lectin involved in innate immunity. Human MBL is complexed with three types of serine proteases (MASP‐1, MASP‐2 and MASP‐3) and two types of their truncated forms (sMAP and MAp44). When an MBL complex binds to carbohydrates of pathogens, the complement system is activated via the lectin pathway. Human MBL is a mixture of different sized oligomers that range mainly from trimers to hexamers. It has been suggested that different MBL oligomers may have distinct MASP compositions. In the present study, an MBL trimer (MBL‐I) exclusive of other oligomers was isolated from human serum by chromatography. Immunoblot analysis of MBL‐I revealed that it had been co‐purified with MASP‐1 and sMAP. This suggests that MASP‐1 and sMAP are bound to each other in MBL‐I. The MBL‐I complex was found to activate C2, but to lack the ability to activate C4 due to the absence of MASP‐2.