Figure 24-37. The V-J joining process involved in making a human κ light chain.

Figure 24-37The V-J joining process involved in making a human κ light chain

In the “germ-line” DNA (where the antibody genes are not being expressed and are therefore not rearranged), the cluster of five J gene segments is separated from the C-region exon by a short intron and from the 40 V gene segments by thousands of nucleotide pairs. During the development of a B cell, the randomly chosen V gene segment (V3 in this case) is moved to lie precisely next to one of the J gene segments (J3 in this case). The “extra” J gene segments (J4 and J5) and the intron sequence are transcribed (along with the joined V3 and J3 gene segments and the C-region exon) and then removed by RNA splicing to generate mRNA molecules in which the V3, J3, and C sequences are contiguous. These mRNAs are then translated into κ light chains. A J gene segment encodes the C-terminal 15 or so amino acids of the V region, and the V-J segment junction coincides with the third hypervariable region of the light chain, which is the most variable part of the V region.

From: The Generation of Antibody Diversity

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

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