Question

What happensWhen MBL/Ficolin gets activated (i.e. binds ligand)? (what are the steps of lectin activation, 9)

A) Ligand binding induces conformational changes in MBL/Ficolin, exposing binding sites for C1q.

B) MBL/Ficolin binding triggers the activation of C3 convertase through the lectin pathway.

C) C1s cleaves MBL/Ficolin-bound C4 and C2, initiating the formation of C3 convertase.

D)The activated lectin pathway results in the opsonization and lysis of the pathogen.

Answer 1

Activation of MBL/Ficolin during the lectin pathway leads to the cleavage of C4 and C2, the formation of C3 convertase, and subsequently, the production of C3b for opsonization, C3a for phagocyte attraction, and the MAC for pathogen lysis.

Step-by-step explanation:

When MBL/Ficolin gets activated, meaning it binds to a ligand on the surface of a pathogen, it triggers a series of events known as the lectin pathway of complement activation. This pathway is similar to the classical and alternative complement pathways, both of which lead to the destruction of pathogens. Upon ligand binding, MBL/Ficolin undergoes a conformational change that leads to the activation of associated proteases called MASPs (MBL-associated serine proteases). These proteases then cleave C4 and C2 to form the C3 convertase, which is a key step in the complement cascade. The result of the conversion is the production of C3b, which opsonizes the pathogen, and C3a, which attracts phagocytes. Eventually, the cascade culminates with the formation of the membrane-attack complex (MAC), which can lyse the pathogen.