Key points are not available for this paper at this time.
In CSR, the C region is replaced by downstream C, C, or C segments to generate IgG, IgE, and IgA antibodies, respectively. This process is mediated by an intrachromosomal recombinational event between the switch (S) region of the C region (S) and one of the downstream S regions (Fig. These S regions are located immediately upstream of each of the C regions (except for ; Fig.
Li et al. (2004) studied this question.