mannan-binding lectin serine protease 1; complement factor MASP-3; complement-activating component of Ra-reactive factor; mannose-binding lectin-associated serine protease 1; MASP-1; mannose-binding protein-associated serine protease; Ra-reactive factor serine protease p100; RaRF; serine protease 5; contains: mannan-binding lectin serine protease 1 heavy chain; mannan-binding lectin serine protease 1 light chain (MASP1, CRARF, CRARF1, PRSS5)
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Function
- functions in the lectin pathway of complement, which performs a key role in innate immunity by recognizing pathogens through patterns of sugar moieties & neutralizing them
- the lectin pathway is triggered upon binding of mannan-binding lectin & ficolins to sugar moieties which leads to activation of the associated proteases MASP1 & MASP2
- functions as an endopeptidase & may activate MASP2 or complement-C2 or directly activate complement-C3
- isoform 2 may have an inhibitory effect on the activation of the lectin pathway of complement or may cleave IGFBP5
- inhibited by SERPING1 & A2M
- iron & 2-oxoglutarate dependent 3-hydroxylation of Asp & Asp is (R) stereospecific within EGF domains
- some N-linked glycan are of the complex-type
- autoproteolytic processing of the proenzyme produces the active enzyme composed of a heavy & the light chain held together by a disulfide bond
- isoform 1 but not isoform 2 is activated through autoproteolytic processing
interacts with the oligomeric lectins MBL2, FCN2 & FCN3; triggers the lectin pathway of complement through activation of complement-C3
interacts with SERPING1
- KM=0.10 mM for Ac-Gly-Lys-OMe (at 30 degrees celsius)
- KM=310 uM for Bz-Arg-OEt (at 30 degrees celsius)
- KM=4.8 uM for C2 (at 37 degrees celsius)
Structure
- homodimer
- N-glycosylated
- glycosylated on Asn-533 & Asn-599
- belongs to the peptidase S1 family
- contains 2 CUB domains
- contains 1 EGF-like domain
- contains 1 peptidase S1 domain
- contains 2 Sushi (CCP/SCR) domains
Compartment
Alternative splicing
named isoforms=4
Expression
- protein of the plasma which is primarily expressed by liver
Pathology
- defects in MASP1 are the cause of 3MC syndrome type 1
Polymorphism
- variant in position: 497:H->Y (in 3MC1)
- variant in position: 630:C->R (in 3MC1)
- variant in position: 666:G->E (in 3MC1)