The immunoglobulin heavy chain locus contains another B-cell-specific 3' enhancer close to the alpha constant region.

The transcription of immunoglobulin genes is controlled by variable region promoters and by enhancers, both of which are lymphoid specific. Because immunoglobulin genes are subject to an extremely complex regulation, we anticipated that there might be additional control elements for these genes. We therefore sought additional enhancers and demonstrate here that there is indeed another weak transcriptional enhancer just 3' to the mouse alpha constant region. This novel immunoglobulin enhancer is lymphoid specific and at two positions can bind members of the Oct family of transcription factors.