Talk:72F fusion protein

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Antigen Receptor Diversity The human genome is presently estimated to contain 20–25 thousand genes. The number of T-cell receptors for antigen (TCRs) that we make is estimated at 2.5 x 107; the number of different kinds of antibody molecules (BCRs) is probably about the same.

Link to discussion of the structure of BCRs and TCRs.

How could 2.5 x 104 genes encode 2.5 x 107 different TCRs and the same number of different BCRs?

The answer: each receptor chain

heavy (H) plus kappa (κ) or lambda (λ) chains for BCRs; alpha (α) and beta (β) or gamma (γ) and delta (δ) chains for TCRs) is encoded by several different gene segments. The genome contains a pool of gene segments for each type of chain. Random assortment of these segments makes the largest contribution to receptor diversity.