Question

You have generated three different strains of mice each strain completely missing the complement protein indicated in the table below, Predict the effect of each missing protein on the event indicated in the 1 column of the table. Fill in the table (each box labeled 1-9) with one of the following symbols: (12 pts.) NE = no effect on the event because none of the complement pathways are blocked D = event will be decreased. but not eliminated because some, but not all complement pathways are blocked 1 = event will be increased because some complement pathways are enhanced A =event will be completely eliminated because all complement pathways are blocked Strain 3 C6 Strain 2 Factor B Mouse Type Missing Protein Strain 1 C2 Formation of Membrane-bound C3 Convertase Formation of Membrane Attack Complex Formation of Anaphylatoxins Justify your answers above by briefly describing the role of C2, Factor B and C6 in the normal functioning of the complement system.

Answer 1

• C2: In the classical and lectin pathways of complement activation system, C2 acts as a multi-domain serine protease. C2 binds to C4b in the presence of Ca ²⁺ , which later is cleaved to C2b, and is thereafter, responsible for the activation C3- and C5-convertases.
• Factor B: This protein is present in the alternative pathway of complement activation. It is cleaved to form Bb fragment by Factor D, and this fragment acts as like the C3 convertase of the alternative pathway.
• C6: In all the complement pathways, this protein is present, and is part of the membrane attack complex (MAC), and it can insert into the cell membrane causing the cell to lyse.

CLASSICAL LECTIN رام رادMP Cart, (16* 4 MASPSA ALTERNATIVE c3 L C3 (40) facter B, Dt 63 (4₂0) Bb 3 cza Cababt 23 (3-convertases a cab 7 (36k factor Blo* (3b C3 at (36 Bb* (4626* (3b 15 (3a opsonization Co-convertases Y Cob inflammation, cell migration, o activation сэbвь*cзь cs 15 156 1667 C6 C7 & C3a sa anaphylotoxins is a ca a csa [656-91 (Membrane Attack Complex) cell cysis ia 7 pore formation

1. A
2. NE
3. NE
4. NE
5. D
6. D
7. D
8. NE
9. NE