An immunoglobulin deletion mutant with implications for the heavy-chain switch and RNA splicing

Abstract

The IF2 immunoglobulin mutant is a DNA deletion of one coding segment and large sections of the flanking intervening sequences. The deletion results in a new splicing pattern and starts in a DNA region containing tandemly repeated sequences which may carry heavy-chain class switch signals.

Interruption of two immunoglobulin heavy-chain switch regions in murine plasmacytoma P3.26Bu4 by insertion of retroviruslike element ETn.

“…However, the IF2 heavy chain lacks the first constant-region domain (1). The gene from which this protein is expressed has suffered a deletion that begins in S-yl sequences and extends downstream, removing much of the J-C intron, all of the first C-yl exon, and some of the C-yl-hinge intron (12). Thus, the expressed -yl gene of IF2 is rearranged relative to the expressed gene of P3.…”

Expression and regulation of immunoglobulin heavy chain gene transfected into lymphoid cells.

“…The enhancer element would therefore be maintained in VH rearrangements to any of the four JH segments and would retain its position with respect to the VH exon following heavy chain class-switching. Deletions extending into the large intron of the CH locus but which do not abolish immunoglobulin heavy chain expression have been observed (Dunnick et al, 1980; …”

Regulation of AID, the B-cell genome mutator

“…Each C H region has unique repeats; however, these regions frequently contain short motifs, such as GAGCT or TGGGG (Dunnick et al 1980;Kataoka et al 1981). Recombination sites can be located throughout the tandem repeats or at the 59 end, middle, or 39 end of the switch region (Dunnick et al 1993).…”