In the alternative complement pathway, the C3 convertase that cleaves C3 into C3a and C3b is composed of which of the following?
- A C3bBb ✓
- B C4b2a
- C C3(H2O)Bb
- D C4b2a3b
Correct answer: A. C3bBb
Explanation
The alternative pathway C3 convertase is C3bBb, formed when factor A binds to spontaneously hydrolyzed C3 (C3(H2O)) or surface-deposited C3b, then is cleaved by factor D. C4b2a is the classical/lectin pathway C3 convertase. C3(H2O)Bb is the initial fluid-phase alternative pathway convertase that generates more C3b. C4b2a3b is the classical pathway C5 convertase.
Reference: Janeway's Immunobiology, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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