MICR 3230 Lecture Notes - Lecture 5: Complement Membrane Attack Complex, C5-Convertase, Complement System
25 Oct 2018
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Document Summary
The term compliment refers to a set of serum proteins that cooperate with the immune system to eliminate blood and tissue pathogens. Various complement components bind and opsonize bacteria. Some complement proteins elicit inflammatory responses, clear immune complexes from the serum, and/or eliminate apoptotic cells. Also, a membrane attack complex (mac) assembled from complement proteins directly kills some pathogens by creating pores in microbial membranes. Proteins involved in complement system: complement pathways are initiated by proteins that bind to pathiogens (directly or via antibody, enzymes generate the central portion of the complement cascade (c3 and c5 convertases) Although the initiating event of each of the three pathways is different, they all converge in the generation of an enzyme complex capable of cleaving the c3 molecule into two fragments, c3a and c3b. C1q binds to antigen-antibody complexes and activates c1r. The activated c1r activates c1s, which in turn cleaves c4 to c4a and c4b.
