Search results for MASP1

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Protein (3 results from a total of 3)

Identifier: R-HSA-182686
Species: Homo sapiens
Compartment: extracellular region
Primary external reference: UniProt: MASP1: P48740
Identifier: R-HSA-166687
Species: Homo sapiens
Compartment: extracellular region
Primary external reference: UniProt: P48740
Identifier: R-HSA-182685
Species: Homo sapiens
Compartment: extracellular region
Primary external reference: UniProt: P48740

Complex (4 results from a total of 4)

Identifier: R-HSA-182687
Species: Homo sapiens
Compartment: extracellular region
The two MASP2 fragments are linked via a disulphide bond between positions 434 and 552
Identifier: R-HSA-166693
Species: Homo sapiens
Compartment: extracellular region
Identifier: R-HSA-2981041
Species: Homo sapiens
Compartment: extracellular region
Identifier: R-HSA-166713
Species: Homo sapiens
Compartment: extracellular region

Pathway (1 results from a total of 1)

Identifier: R-HSA-166662
Species: Homo sapiens
Activation of the lectin pathway (LP) is initiated by Mannose-binding lectin (MBL), the hetero-complex CL-LK formed from COLEC11 (Collectin liver 1, CL-L1) and COLEC10 (Collectin kidney 1, CL-K1), and the ficolins (FCN1, FCN2, FCN3). All are Ca-dependent (C-type) lectins that initiate the complement cascade after binding to specific carbohydrate patterns on the target cell surface. All form trimers and larger oligomers (Jensen et al. 2005, Dommett et al. 2006, Garlatti et al. 2010). MBL and ficolins circulate in plasma as complexes with homodimers of MBL-associated serine proteases (MASP) (Fujita et al. 2004, Hajela et al. 2002). MASP1, MASP2 and MASP3 have all been reported to mediate complement activation. Upon binding of human lectin to the target surface, the complex of lectin:MASP undergoes conformational changes that result in MASP cleavage and activation (Matsushita M et al. 2000, Fujita et al. 2004). Active MASP2 cleaves C4 to generate C4a and C4b. C4b binds to the target cell surface via its thioester bond, then binds circulating C2 (Law and Dodds 1997). Bound C2 is cleaved by MASP2 to yield the C3 convertase C4b:C2a. The active form of MASP1 was reported to cleave C2 in a manner similar to MASP2 (Matsushita et al. 2000, Chen & Wallis 2004). MASP1 can cleave proenzyme MASP2, leading to complement activation (Heja et al. 2012). MASP1 can also cleave fibrinogen to yield fibrinopeptide B, and activates factor XIII. MASP1 may have a role in removal of 'dead C3', i.e. C3(H2O) (Hajela et al. 2002). In addition to MASP1 to 3, two alternatively-slpiced forms of MASP1 (MAp44) and MASP2 (sMAP) have been implicated in complement cascade signaling (Takahashi et al. 1999, Degn et al. 2010). The functions of MASP3, sMAP and MAp44 in the lectin pathway remain to be clarified.

Reaction (2 results from a total of 2)

Identifier: R-HSA-8852509
Species: Homo sapiens
Compartment: extracellular region, plasma membrane
Collectin kidney 1 (CL-K1, CL-11, COLEC11) (Keshi et al. 2006) forms disulfide-bridged stable heteromers with collectin liver 1 (CL-L1, COLEC10) (Otahani et al. 1999), with a ratio of one COLEC10 to two COLEC11 polypeptide chains. The majority of plasma COLEC11 was found in complex with COLEC10 (Henriksen et al. 2013). The resulting COLEC10:2xCOLEC11 heterocomplex, termred CL-LK, contains multiple Ca2+ -dependent carbohydrate-recognition domains (CRDs) and collagen-like regions, which allow high-avidity binding (KD ~10-9 M) to target cell surface carbohydrate patterns (Bajic et al. 2015); COLEC11 recognizes L-fucose and D-mannose and the disaccharide D-mannose(alpha1-2)-D-mannose (Keshi et al. 2006, Hansen et al. 2010, Selman & Hansen 2012, ). CL-LK can bind mannose-rich patterns on M. tuberculosis (Troegeler et al. 2015). The CL-LK complex was able to bind mannan-binding lectin-associated serine proteases (MASPs) in vitro with affinities in the nM range, and was associated with MASP1/3 and MASP2 in plasma. Upon binding to mannan or DNA in the presence of MASP2, the COLEC10:COLEC11 complex mediated deposition of C4b (Henriksen et al. 2013). Polymorphisms in the COLEC11 gene cause 3MC syndrome (Rooryck et al. 2011).
Identifier: R-HSA-166721
Species: Homo sapiens
Compartment: extracellular region, plasma membrane
The MBL polypeptide chain consists of a short N-terminal cysteine-rich region, a collagen-like region comprising 19 Gly-X-Y triplets, a 34-residue hydrophobic stretch, and a C-terminal C-type lectin domain. MBL monomers associate via their cysteine-rich and collagen-like regions to form homotrimers, and these in turn associate into oligomers. The predominant oligomers found in human serum contain three (MBL-I) or four (MBL-II) homotrimers (Fujita et al. 2004, Teillet et al. 2005). Extracellular MBL oligomers circulate as complexes with MASP1/2. In the presence of Ca2+, the carbohydrate recognition domain (CRD) of MBL binds carbohydrates with 3- and 4- OH groups in the pyranose ring, such as mannose and N-acetyl-D-glucosamine. Such motifs occur on the surfaces of viruses, bacteria, fungi and protozoa. The affinity of any one MBL binding site for a carbohydrate ligand is low, but interaction between multiple binding sites on an MBL oligomer and repetitive carbohydrate motifs on a target cell surface allow high-avidity binding. The specificity of the MBL binding site (it does not bind glucose or sialic acid) and the requirement for a repeated target motif may account for the failure of MBL to bind human glycoproteins under normal conditions (Petersen et al. 2001). This reaction in particular represents the interaction of MBL with bacterial mannose repeats.
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