UCSD Molecule Pages
Published online: 25 Mar 2013 | doi:10.6072/H0.MP.A004276.01
Basis Sequence: Human
Ashok Reddy Dinasarapu1, Anjana Chandrasekhar1, Teizo Fujita2, Shankar Subramaniam3
1Department of Bioengineering, University of California, San Diego, CA 92093, US. 2Dept. of Immunology, Fukushima Medical University, 960-1295, JP. 3Department of Bioengineering, University of California at San Diego, CA 92093, US.
Correspondence should be addressed to Ashok Reddy Dinasarapu: email@example.com
Mannose/mannan-binding lectin (MBL) is a serum lectin synthesized (as a ~32 kDa peptide) by the liver and is one of the key molecules of the innate immune system. Each peptide has an N (amino)-terminal cysteine-rich region, a middle stretch of a collagen-like sequence, and a carbohydrate recognition domain (CRD) in the C (carboxy)-terminus. Three identical peptides form a structural subunit, similar to a collagenous triple helix, which is the basic building block of all circulating molecular forms of MBL. Further oligomerization of these structural subunits by disulphide bonds in the N-terminal region results in MBL molecules of different sizes (from dimers to hexamers), but the hexameric form is probably the most common. MBL-associated serine proteases (MASPs) bind to MBL multimeric forms to stabilize the molecule. MBL is a pattern-recognition receptor and the CRDs of MBL serve to bind to a wide range of pathogens such as bacteria, viruses and protozoa, by recognizing carbohydrate moieties on their surfaces. There are two pathways by which MBL can participate in a host defense response: 1) MBL activates the lectin complement pathway via MASPs, that converges with the classical complement pathway, at the level of complement C4 (C4-A or C4-B), and 2) MBL may also act directly as an opsonin, enhancing phagocytosis by binding to cell-surface receptors present on phagocytic cells.
Alternative names for this molecule:
COLEC1; Collectin-1; HSMBPC; Mannan-binding lectin; Mannan-binding protein; Mannose-binding lectin; Mannose-binding lectin (protein C) 2, soluble; Mannose-binding lectin (protein C) 2, soluble (opsonic defect); Mannose-binding lectin 2, soluble (opsonic defect); Mannose-binding protein C; Mannose/mannan-binding lectin; MBL; MBL2; MBL2D; MBP; MBP-C; MBP1
The UCSD Signaling Gateway Molecule Pages (SGMP) is funded by NIH/NIGMS Grant 1 R01 GM078005-01. The authors thank Dr. John D. Lambris, University of Pennsylvania School of Medicine, Philadelphia, UCSD-SGMP editorial board member, for extensive discussions.