Figure 3.

Schematic diagram of gene-specific targeted hypermutation in immunoglobulin gene loci. The mutation rate is greatly increased only in the variable part of the genome, which is an approximately 1.5 kb region in each of the three immunoglobulin loci. In this figure, the graph above the rearranged variable (V) and joining (J) gene segments that form the variable region of Igκ depicts the mutation domain in the κ-light chain (Igκ) locus. 3′Eκ, Igκ 3′ enhancer; Cκ, Igκ constant; iEκ, Igκ intronic enhancer; MAR, matrix attachment region [23]. (Online version in colour.)