REGULATORS OF THE COMPLEMENT PATHWAY

Question 1

Dissociates C1r and C1s from C1q

Answer 1

C1 inhibitor (C1-INH)

Question 2

• Cleaves C3b and C4b
• The activity can be enhanced by Factor H and
C4-binding protein

Answer 2

Factor I

Question 3

Cofactor with I to inactivate C3b; prevents binding of B to C3b

Answer 3

Factor H

Question 4

Acts as a cofactor with I to inactivate C4b
(C4bp)

Answer 4

C4-binding protein

Question 5

• Prevents attachment of the C5b67 complex to
cell membranes
• Attack the membrane attack phase
C8 will not be initiated

Answer 5

S protein (vitronectin)

Question 6

Among the regulators of complement pathway, which among has the highest molecular weight?

Answer 6

C4-binding protein

Question 7

Among the regulators of complement pathway, which among has the lowest molecular weight?

Answer 7

S protein (vitronectin)

Question 8

Among the regulators of complement pathway, which among has the highest concentration?

Answer 8

S protein

Question 9

Among the regulators of complement pathway, which among has the lowest concentration?

Answer 9

Factor I