Question

SHM and CSR are both dependent on the activity of which of the following enzymes?

A. AID
B. RAG-1/2
C. Artemis
D. DNA uridine glycosylase
E. Both A and D are required for SHM and CSR.

Answer 1

The enzyme required for both SHM and CSR is Activation-Induced cytidine Deaminase (AID), which facilitates the diversification of antibodies.

Step-by-step explanation:

SHM (Somatic Hypermutation) and CSR (Class Switch Recombination) are both processes that are integral to the diversification of antibody production in B cells. They are highly dependent on the activity of a particular enzyme. While both processes involve changes in the immunoglobulin (Ig) genes within B cells to enhance the immune system's ability to combat pathogens, the question pertains specifically to the enzyme required for these mechanisms. The correct answer is A. AID (Activation-Induced cytidine Deaminase). This is the enzyme that initiates both SHM and CSR by deaminating cytidine residues to uridine in Ig genes, which then leads to the necessary modifications to produce diverse and high-affinity antibodies through point mutations or class switch recombination.