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Gene Review

MASP1  -  mannan-binding lectin serine peptidase 1...

Homo sapiens

Synonyms: 3MC1, CRARF, CRARF1, Complement factor MASP-3, Complement-activating component of Ra-reactive factor, ...
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Disease relevance of MASP1


Psychiatry related information on MASP1


High impact information on MASP1

  • MBL is structurally related to the complement C1 subcomponent, C1q, and seems to activate the complement system through an associated serine protease known as MASP (ref. 4) or p100 (ref. 5), which is similar to C1r and C1s of the classical pathway [6].
  • MASP-1, MAp19, and direct C3-cleaving activity are associated with smaller oligomers whereas MASP-3 is found together with MASP-2 on larger oligomers [7].
  • MASP exhibited both C4- and C2-consuming activities [8].
  • Based on analyses of molecular size, antigenicity, and 11 NH2-terminal amino acid sequences of the L chain, we conclude that MASP is a novel protein different from C1r or C1s [8].
  • MASP, C1r and C1s belong to the same family of serine proteases [9].

Biological context of MASP1


Anatomical context of MASP1


Associations of MASP1 with chemical compounds

  • MASP-1 and MASP-3 are alternative splice products of a single gene, MASP1/3, and have identical A chains, whereas they have individual B chains, encompassing the serine protease domain [17].
  • It is likely that human MASP1 is able to activate C3, while human MASP2 cleaves C4, although further functional studies are required to confirm this [18].
  • M-ficolin-MASP complexes activated complement on N-acetylglucosamine (GlcNAc)-coated microplates in a C4 deposition assay [19].
  • On an anti-MASP-1 column, MASP-2 passed through the column in the presence of EDTA and high salt concentration, whereas MASP-1 was retained [20].
  • Western blotting analysis showed the presence of MASP-1, MASP-2, MASP-3, and sMAP in H-ficolin preparations isolated from Cohn Fraction III [21].
  • This information allows us to propose a model of the MBL-MASP-1/3 interaction, involving a major electrostatic interaction between two acidic Ca(2+) ligands of MASP-1/3 and a conserved lysine of MBL [22].

Physical interactions of MASP1


Enzymatic interactions of MASP1

  • In this communication, we report that MASP is unique in having the proteolytic capacity to cleave C3 with subsequent activation of the alternative pathway, a capacity which C1s lacks [25].
  • MASP-1 can cleave C2, and with low efficiency also C3, and may serve a function through direct C3 activation [26].

Regulatory relationships of MASP1

  • MASP-1/3 promoter activity was also down-regulated by IFN-gamma [11].
  • By analogy, one may thus speculate that, upon binding of MBL to carbohydrate, MASP-1 autoactivates and then activates MASP-2, but there is as yet no evidence for this [27].
  • The ability of MBL to activate the complement cascade was tested in a heterologous system by deposition of human C4 on the chicken MBL/MASP complex [28].

Other interactions of MASP1

  • Isolated MASP-1 and MASP-2 exhibited proteolytic activities against C3 and C4, respectively [20].
  • C1 inhibitor (C1 INH), an inhibitor for C1r and C1s, formed equimolar complexes with MASP-1 and MASP-2 and inhibited their proteolytic activities [20].
  • SDS-PAGE and immunoblotting analyses showed the secreted H-ficolin/Hakata antigen, MASP-1 and MASP-3 to be 34, 81 and 105 kDa in size respectively, similar to their serum counterparts [1].
  • It has been reported recently that L-ficolin/P35 associates with mannan-binding lectin (MBL)-associated serine proteases (MASP-1 and -2) and MBL-associated protein 19 (MAp19) in serum and forms complexes able to activate complement [29].
  • The deposited MBL/MASP-1 was observed to associate with C3b/C3c and C5b-9 but not with IgG, IgM, C1q, C4c, or properdin [2].

Analytical, diagnostic and therapeutic context of MASP1


  1. Expression of H-ficolin/Hakata antigen, mannose-binding lectin-associated serine protease (MASP)-1 and MASP-3 by human glioma cell line T98G. Kuraya, M., Matsushita, M., Endo, Y., Thiel, S., Fujita, T. Int. Immunol. (2003) [Pubmed]
  2. Glomerular deposition of mannose-binding lectin (MBL) indicates a novel mechanism of complement activation in IgA nephropathy. Endo, M., Ohi, H., Ohsawa, I., Fujita, T., Matsushita, M., Fujita, T. Nephrol. Dial. Transplant. (1998) [Pubmed]
  3. The C4 and C2 but not C1 components of complement are responsible for the complement activation triggered by the Ra-reactive factor. Ji, Y.H., Matsushita, M., Okada, H., Fujita, T., Kawakami, M. J. Immunol. (1988) [Pubmed]
  4. Substrate specificities of recombinant mannan-binding lectin-associated serine proteases-1 and -2. Rossi, V., Cseh, S., Bally, I., Thielens, N.M., Jensenius, J.C., Arlaud, G.J. J. Biol. Chem. (2001) [Pubmed]
  5. Enhancement of complement activation and opsonophagocytosis by complexes of mannose-binding lectin with mannose-binding lectin-associated serine protease after binding to Staphylococcus aureus. Neth, O., Jack, D.L., Johnson, M., Klein, N.J., Turner, M.W. J. Immunol. (2002) [Pubmed]
  6. A second serine protease associated with mannan-binding lectin that activates complement. Thiel, S., Vorup-Jensen, T., Stover, C.M., Schwaeble, W., Laursen, S.B., Poulsen, K., Willis, A.C., Eggleton, P., Hansen, S., Holmskov, U., Reid, K.B., Jensenius, J.C. Nature (1997) [Pubmed]
  7. MASP-3 and its association with distinct complexes of the mannan-binding lectin complement activation pathway. Dahl, M.R., Thiel, S., Matsushita, M., Fujita, T., Willis, A.C., Christensen, T., Vorup-Jensen, T., Jensenius, J.C. Immunity (2001) [Pubmed]
  8. Activation of the classical complement pathway by mannose-binding protein in association with a novel C1s-like serine protease. Matsushita, M., Fujita, T. J. Exp. Med. (1992) [Pubmed]
  9. Complement-related serine proteases in tunicates and vertebrates. Matsushita, M., Endo, Y., Nonaka, M., Fujita, T. Curr. Opin. Immunol. (1998) [Pubmed]
  10. The human gene for mannan-binding lectin-associated serine protease-2 (MASP-2), the effector component of the lectin route of complement activation, is part of a tightly linked gene cluster on chromosome 1p36.2-3. Stover, C., Endo, Y., Takahashi, M., Lynch, N.J., Constantinescu, C., Vorup-Jensen, T., Thiel, S., Friedl, H., Hankeln, T., Hall, R., Gregory, S., Fujita, T., Schwaeble, W. Genes Immun. (2001) [Pubmed]
  11. Functional characterization of human mannose-binding lectin-associated serine protease (MASP)-1/3 and MASP-2 promoters, and comparison with the C1s promoter. Endo, Y., Takahashi, M., Kuraya, M., Matsushita, M., Stover, C.M., Schwaeble, W.J., Fujita, T. Int. Immunol. (2002) [Pubmed]
  12. A novel truncated isoform of the mannose-binding lectin-associated serine protease (MASP) from the common carp (Cyprinus carpio). Nagai, T., Mutsuro, J., Kimura, M., Kato, Y., Fujiki, K., Yano, T., Nakao, M. Immunogenetics (2000) [Pubmed]
  13. Detection of a processed pseudogene of the human MBL-associated serine protease, MASP1. Mochihara, Y., Tazawa, H., Habuta, S., Ohthubo, K., Kozaki, T., Ishihara, Y., Takayama, Y., Kawakami, M. Cytogenet. Genome Res. (2002) [Pubmed]
  14. Mannose-binding lectin (MBL) in health and disease. Turner, M.W. Immunobiology (1998) [Pubmed]
  15. Human serum mannose-binding lectin (MBL)-associated serine protease-1 (MASP-1): determination of levels in body fluids and identification of two forms in serum. Terai, I., Kobayashi, K., Matsushita, M., Fujita, T. Clin. Exp. Immunol. (1997) [Pubmed]
  16. Lectin complement system and pattern recognition. Endo, Y., Takahashi, M., Fujita, T. Immunobiology (2006) [Pubmed]
  17. The mannan-binding lectin-associated serine proteases (MASPs) and MAp19: four components of the lectin pathway activation complex encoded by two genes. Schwaeble, W., Dahl, M.R., Thiel, S., Stover, C., Jensenius, J.C. Immunobiology (2002) [Pubmed]
  18. MASP1 (MBL-associated serine protease 1). Matsushita, M., Endo, Y., Fujita, T. Immunobiology (1998) [Pubmed]
  19. Human M-ficolin is a secretory protein that activates the lectin complement pathway. Liu, Y., Endo, Y., Iwaki, D., Nakata, M., Matsushita, M., Wada, I., Inoue, K., Munakata, M., Fujita, T. J. Immunol. (2005) [Pubmed]
  20. Proteolytic activities of two types of mannose-binding lectin-associated serine protease. Matsushita, M., Thiel, S., Jensenius, J.C., Terai, I., Fujita, T. J. Immunol. (2000) [Pubmed]
  21. Activation of the lectin complement pathway by H-ficolin (Hakata antigen). Matsushita, M., Kuraya, M., Hamasaki, N., Tsujimura, M., Shiraki, H., Fujita, T. J. Immunol. (2002) [Pubmed]
  22. Crystal structure of the CUB1-EGF-CUB2 domain of human MASP-1/3 and identification of its interaction sites with mannan-binding lectin and ficolins. Teillet, F., Gaboriaud, C., Lacroix, M., Martin, L., Arlaud, G.J., Thielens, N.M. J. Biol. Chem. (2008) [Pubmed]
  23. Role of L-ficolin/mannose-binding lectin-associated serine protease complexes in the opsonophagocytosis of type III group B streptococci. Aoyagi, Y., Adderson, E.E., Min, J.G., Matsushita, M., Fujita, T., Takahashi, S., Okuwaki, Y., Bohnsack, J.F. J. Immunol. (2005) [Pubmed]
  24. alpha 2-Macroglobulin binds to and inhibits mannose-binding protein-associated serine protease. Terai, I., Kobayashi, K., Matsushita, M., Fujita, T., Matsuno, K. Int. Immunol. (1995) [Pubmed]
  25. Cleavage of the third component of complement (C3) by mannose-binding protein-associated serine protease (MASP) with subsequent complement activation. Matsushita, M., Fujita, T. Immunobiology (1995) [Pubmed]
  26. Mannan-binding-lectin-associated serine proteases, characteristics and disease associations. Sørensen, R., Thiel, S., Jensenius, J.C. Springer Semin. Immunopathol. (2005) [Pubmed]
  27. MASP-2, the C3 convertase generating protease of the MBLectin complement activating pathway. Vorup-Jensen, T., Jensenius, J.C., Thiel, S. Immunobiology (1998) [Pubmed]
  28. Serum levels of mannan-binding lectin in chickens prior to and during experimental infection with avian infectious bronchitis virus. Juul-Madsen, H.R., Munch, M., Handberg, K.J., Sørensen, P., Johnson, A.A., Norup, L.R., Jørgensen, P.H. Poult. Sci. (2003) [Pubmed]
  29. Characterization of the interaction between L-ficolin/p35 and mannan-binding lectin-associated serine proteases-1 and -2. Cseh, S., Vera, L., Matsushita, M., Fujita, T., Arlaud, G.J., Thielens, N.M. J. Immunol. (2002) [Pubmed]
  30. Interaction properties of human mannan-binding lectin (MBL)-associated serine proteases-1 and -2, MBL-associated protein 19, and MBL. Thielens, N.M., Cseh, S., Thiel, S., Vorup-Jensen, T., Rossi, V., Jensenius, J.C., Arlaud, G.J. J. Immunol. (2001) [Pubmed]
  31. Mannose-binding lectin engagement with late apoptotic and necrotic cells. Nauta, A.J., Raaschou-Jensen, N., Roos, A., Daha, M.R., Madsen, H.O., Borrias-Essers, M.C., Ryder, L.P., Koch, C., Garred, P. Eur. J. Immunol. (2003) [Pubmed]
  32. Improvements on the purification of mannan-binding lectin and demonstration of its Ca(2+)-independent association with a C1s-like serine protease. Tan, S.M., Chung, M.C., Kon, O.L., Thiel, S., Lee, S.H., Lu, J. Biochem. J. (1996) [Pubmed]
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