An IgH Enhancer That Drives Transcription through Basic Helix-Loop-Helix and Oct Transcription Factor Binding Motifs: FUNCTIONAL ANALYSIS OF THE Eµ3′ ENHANCER OF THE CATFISH *

摘要: The transcriptional enhancer (Eµ3′) of the IgH locus channel catfish, Ictalurus punctatus, shows strong B cell-specific activity and differs from mammalian Eµ in both location structure. It occurs between µ δ genes contains numerous transcription factor binding sites, predominantly octamer µE5 motifs consensus variant sequences. lacks classical µA-µE3(CBF)-µB core array seen within enhancers. To determine functionally important motifs, a series mutant enhancers was created using sequence-targeted polymerase chain reaction. Whereas mutation (individually or multiples) decreased function, single motif destroyed function this plasmacytomas. Mutation site, combined with mutations certain catfish cells. Experiments artificial containing multimers short regions native suggested that minimal Eµ3′ (a) site two (b) is cell-specific, (c) active across species. dependence an Ig on sites bind basic helix-loop-helix Oct factors has not previously been observed confirms large differences structure fish