Mannose-binding lectin serine proteases and associated proteins of the lectin pathway of complement: two genes, five proteins and many functions?

Tang Yongqing, Nicole Drentin, Renee C Duncan, Lakshmi C Wijeyewickrema, Robert N Pike

Research output: Contribution to journalArticleResearchpeer-review

50 Citations (Scopus)


The lectin pathway of the complement system is activated following the binding of carbohydrate-based ligands by recognition molecules such as mannose-binding lectin (MBL) or ficolins. Engagement of the recognition molecules causes activation of associated MBL-associated serine proteases or MASPs, which in turn activate downstream complement molecules to activate the system. Two MASP genes are alternatively spliced during expression to yield 5 proteins, including three proteases (MASP-1, -2 and -3) and two truncated proteins, MAp19 and MAp44. Here we discuss what is currently known about these proteins in terms of their structure and function. MASP-2 is autoactivated following the initial binding events of the pathway and is able to subsequently activate the C4 and C2 substrates required to activate the rest of the pathway. MASP-1 is able to augment MASP-2 activation, but also appears to play other roles, although the physiological significance of these is not yet clear. The roles of the truncated Map19 and Map44 proteins and the MASP-3 protease are currently unknown. The proteases form an interesting sub-family of proteins that clearly should be the focus of future research in order to establish their biological roles. This article is part of a Special Issue entitled: Proteolysis 50years after the discovery of lysosome.
Original languageEnglish
Pages (from-to)253 - 262
Number of pages10
JournalBBA Proteins and Proteomics
Issue number1
Publication statusPublished - 2012

Cite this