Page 515 - Veterinary Immunology, 10th Edition

VetBooks.ir Gene Recombination

Gene recombination results from the random selection of one gene
from each of several groups of genes followed by recombining

these selected genes to generate sequence diversity. It is well seen in
the genes that code for immunoglobulins (Table 17.1).

TABLE 17.1

Examples of Different Gene Use in Mammals

Species IGKV IGKJ IGLV IGLJ IGHV IGHJ IGHD
Horses 60 5 144 7 52 8 40
Bovine 22 3 25 4 36 6 14
Sheep 10 3 >100 1 7 6 >1
Pigs 14 5 23 4 20 1 2
Mice 169 9 14 3 161 7 18
Humans 48 9 69 8 215 27 30
Rats 163 7 3 2 174 5 21

Three gene loci code for immunoglobulin peptide chains, and
each is found on a different chromosome (Fig. 17.3). One locus,
called IGL, uses three genes to code for λ light chains; one, called
IGK, uses three genes to code for κ light chains; and one, called IGH,
uses four genes to encode heavy chains.

FIG. 17.3 Genes coding for immunoglobulin light chains and
heavy chains. Note that there are two distinct light chain loci, one
coding for kappa chains and one coding for lambda chains. These
are located on different chromosomes. The precise number of V, D,
and J genes varies among species.

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