The human lambda immunoglobulin enhancer is controlled by both positive elements and developmentally regulated negative elements.

Molecular immunology

PubMedID: 8676894

Glozak MA, Blomberg BB. The human lambda immunoglobulin enhancer is controlled by both positive elements and developmentally regulated negative elements. Mol Immunol. 1996;33(4-5):427-38.
We have recently reported the localization of the first transcriptional enhancer in the human lambda (lambda) immunoglobulin light chain locus. Enhancer activity was contained on a 1.2 kb SstI fragment, with partial activity retained on a core 111 bp PstI-SstI fragment. This enhancer is located 11.7 kb downstream of C lambda 7, the most 3' lambda constant region gene. Using a chloramphenicol acetyl transferase (CAT) assay system, we have now determined the boundaries of the complete enhancer and find it is two- to four-fold as active as the core fragment in both pre-B and B cell lines. Interestingly, a larger fragment, containing the complete enhancer as well as 5' and 3' flanking sequences has four- to eight-fold reduced activity when tested in pre-B cell lines, but full activity in B cell lines. This suggests the presence of developmentally regulated negative elements flanking the human lambda enhancer which prevent or reduce its activity at a developmentally incorrect time. By using in vivo footprinting we have begun to examine the protein interactions within this enhancer in a more physiologically relevant manner and have identified motifs which are shared with the murine lambda enhancers, as well as motifs unique to the human lambda enhancer.