Octamer function in the chicken lambda immunoglobulin light chain promoter.

The chicken immunoglobulin (Ig) lambda light chain promoter contains an octamer motif (-106) and a TATA box (-70). Two lymphoid cell lines, DT40 (B-cell line) and MSB1 (T-cell line), were used to test the activity of the germline promoter and the function of the octamer motif. The promoter was functional only in B cells in the presence of SV40 enhancer. Mutation of the octamer motif eliminated the transcriptional activity of the Ig promoter. These results suggest that the chicken Ig promoter functions similarly to mammalian Ig promoters in that it plays a role in tissue specificity and requires both an enhancer and an intact octamer motif for activity.