DIFFERENTIAL TRANSCRIPTION EFFICIENCY OF 2 IG V-H PROMOTERS IN-VITRO

Ig variable region gene segment is transcribed from its own unique pro moter. While all of these promoters share common consensus elements th at contribute to the B cell-specific expression of these genes, the DN A sequence of each promoter is distinct. In this study, we have direct ly compared the transcription efficiencies of two murine heavy chain ( V-H) promoters in a murine B cell in vitro transcription system. We fo und that the promoters differed in both transcription efficiency and t he ability to bind specific protein complexes. While some of the trans cription differences may be attributed to differences in basal promote r elements, the spacing between the octamer and the heptamer consensus elements was found to be important. Others have reported a direct cor relation between transcription efficiency and the probability that ind ividual variable region gene segments will rearrange. Our studies may be of direct importance to those interested in identifying B cell-spec ific transcription factors and may ultimately help to explain differen ces in the expression of some V-H gene segments.