Transcriptional enhancer elements in the mouse immunoglobulin heavy chain locus.

Two regions in the immunoglobulin heavy chain locus were tested for their ability to enhance transcription of the SV40 early promoter. A portion of the intervening sequence between the heavy chain joining region (Jh) and the constant region of the mu chain (Cmu) can enhance transcription when it is cloned either 5' or 3' to the SV40 early promoter. The region between C alpha and the alpha switch site, which occurs 5' to the translocated c-myc oncogene in many murine plasmacytomas, does not show transcriptional enhancer activity in this assay.