MASP1 (protein)

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External IDsGeneCards: [1]
RefSeq (mRNA)



RefSeq (protein)



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Mannan-binding lectin serine protease 1 also known as mannose-associated serine protease 1 (MASP-1) is an enzyme that in humans is encoded by the MASP1 gene.[1][2][3]

MASP-1 is involved in the lectin pathway of the complement system and is responsible for cleaving C4 and C2 into fragments to form a C3-convertase.[4]


MASP-1 is a serine protease that functions as a component of the lectin pathway of complement activation. The complement pathway plays an essential role in the innate and adaptive immune response. MASP-1 is synthesized as a zymogen and is activated when it complexes with the pathogen recognition molecules of lectin pathway, the mannose-binding lectin and the ficolins. This protein is not directly involved in complement activation but may play a role as an amplifier of complement activation by cleaving complement C2 or by activating another complement serine protease, MASP-2. MASP-1 is also able to cleave fibrinogen and factor XIII and may be involved in coagulation. A splice variant of this gene which lacks the serine protease domain functions as an inhibitor of the complement pathway.[3]

See also


  1. Takada F, Takayama Y, Hatsuse H, Kawakami M (Oct 1993). "A new member of the C1s family of complement proteins found in a bactericidal factor, Ra-reactive factor, in human serum". Biochemical and Biophysical Research Communications. 196 (2): 1003–9. doi:10.1006/bbrc.1993.2349. PMID 8240317.
  2. Sato T, Endo Y, Matsushita M, Fujita T (Apr 1994). "Molecular characterization of a novel serine protease involved in activation of the complement system by mannose-binding protein". International Immunology. 6 (4): 665–9. doi:10.1093/intimm/6.4.665. PMID 8018603.
  3. 3.0 3.1 "Entrez Gene: mannan-binding lectin serine peptidase 1 (C4/C2 activating component of Ra-reactive factor)".
  4. Matsushita M, Thiel S, Jensenius JC, Terai I, Fujita T (Sep 2000). "Proteolytic activities of two types of mannose-binding lectin-associated serine protease". Journal of Immunology. 165 (5): 2637–42. doi:10.4049/jimmunol.165.5.2637. PMID 10946292.

Further reading

External links

This article incorporates text from the United States National Library of Medicine, which is in the public domain.