Ficolins and the lectin complement pathway.
Ficolins, found in various tissues, are a group of proteins containing both a collagen-like and a fibrinogen-like domain. Recently, it was shown that ficolins present in serum are lectins with a common binding specificity for N-acetylglucosamine (GlcNAc). The fibrinogen-like domain is responsible for the carbohydrate binding. Mannose-binding lectin (MBL) is also a collagenous lectin in serum that is specific for GlcNAc and mannose binding. Its domain organization is similar to that of ficolins, except that MBL has a carbohydrate-recognition domain instead of a fibrinogen-like domain. MBL plays a role in innate immunity by acting as an opsonin and activating complement in association with MBL-associated serine protease (MASP) via the lectin pathway. Investigations of two types of human serum ficolins, ficolin/P35 and Hakata antigen, revealed that they are associated with MASPs and sMAP, a truncated protein of MASP-2, and that they activate complement. These findings indicate that serum ficolins are structurally and functionally similar to MBL and have the capacity to activate the lectin pathway and thus have a role in innate immunity.
Matsushita
M
M
Department of Biochemistry, Fukushima Medical University School of Medicine, Japan. mmatsu@fmu.ac.jp
Fujita
T
T
D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000502:physiology*; D037222:Collectins; D003167:Complement Activation; D005260:Female; D006023:Glycoproteins / Q000737:chemistry; D006364:Hedgehogs; D006801:Humans; D037102:Lectins / Q000737:chemistry / Q000502:physiology*; D008358:Mannose / Q000378:metabolism; D050606:Mannose-Binding Protein-Associated Serine Proteases; D051379:Mice; D005810:Multigene Family; D009124:Muscle Proteins / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012486:Salmonella typhimurium / Q000378:metabolism; D017634:Self Tolerance; D012697:Serine Endopeptidases / Q000378:metabolism; D013045:Species Specificity; D013329:Structure-Activity Relationship; D013552:Swine; D000097604:Ficolins
D000117:Acetylglucosamine; D002352:Carrier Proteins; D037222:Collectins; D006023:Glycoproteins; D037102:Lectins; D008358:Mannose; D050606:Mannose-Binding Protein-Associated Serine Proteases; D009124:Muscle Proteins; D012697:Serine Endopeptidases; D000097604:Ficolins; C109662:FCN3 protein, human; C105466:erinacin protein, Erinaceus europaeus