Question

All of the complement pathways share certain components. What are these shared components?

Answer 1

components which are shared or used in all the 3 Component pathways are -

C3b-C5a,C5b,C6,C7,C8,C9

Explanation-

There are 3 complement pathways-

1.classical pathway, triggered either directly by pathogen or indirectly by antibody which binds to the pathogen

In classical Pathway-

*C1--C2a,C4b

*C2a,C4b act as C3 Convertase which convert C3-C3a,C3b)

*C3b cleaves C5-C5a,C5b

*C5b,C6,C7,C8,C9 together forms membrane attack Complex

2.MB-lectin pathway-

In Mannose-binding lectin Pathway they directly activate C2 which converts C4-C4a,C4b.

*C2a,C4b act as C3 Convertase which convert C3-C3a,C3b)

*C3b cleaves C5-C5a,C5b

*C5b,C6,C7,C8,C9 together forms membrane attack Complex

3.Alternative pathway-

This pathway is triggered, when the C3b protein binds directly to a microbe.

*C3b cleaves C5-C5a,C5b

*C5b,C6,C7,C8,C9 together forms membrane attack Complex

So in this pathway---C1-C2a & C4b are not Taking part

That is in all 3 pathways C3b-C5a,C5b,C6,C7,C8,C9 are used