QuestionSBA
QuestionChoice
As above, C3b is first needed before cleavage of C5 occurs.
10000909
d
C5
QuestionChoice
C1 is part of the classical pathway. It must bind at least two Fc domains of an antibody-antigen complex.
10000910
e
C1
QuestionChoice
All pathways act to cleave C3 into C3b using a C3 convertase enzyme. There are two different C3 convertases (C4b2a in classical and lectin, C3bBb in alternative). C3b becomes a core component of C5 convertase, which cleaves C5 into C5b. C5b forms part of the membrane attack complex which perforates pathogens open. People with C3 deficiencies have the most severe infections out of any complement deficiency.
10000906
a
C3
QuestionChoice
Both lectin and classical pathways cleave C4 - the alternative pathway does not.
10000908
c
C4
QuestionChoice
The classical and lectin pathways both act on C2 - the alternative pathway does not.
10000907
b
C2
Concept
Chapter
2693
3848
The complement system
Topic
158
Immunology
12728
In the complement system, the three pathways all converge to cleave which component?
a