THE 3'-UNTRANSLATED REGION OF MEMBRANE EXON-2 FROM THE GAMMA-2A IMMUNOGLOBULIN GENE CONTRIBUTES TO EFFICIENT TRANSCRIPTION TERMINATION

Elements of the mouse Immunoglobulin gamma 2a gene, near the membrane specific poly(A) addition site, were inserted into a heterologous loca tion in either a synthetic mouse gamma 2b gene or a gpt/SV40 chimeric gene and then assayed for their ability to terminate RNA polymerase II transcription in isolated nuclei of transfected myeloma cells, The in tact gamma 2a membrane specific 3'-untranslated region, with its poten tial stem loop forming sequences and poly(A) site, is able to efficien tly terminate transcription in the absence of the downstream region in which transcription normally terminates (term). Termination efficienc y in the presence of the termination fragment decreases either when se quences specifying a potential stem/loop, upstream of the poly(A) regi on, are interrupted or when the stronger membrane poly(A) site is subs tituted with a weaker, secretory specific poly(A) site. We therefore c onclude that the gamma 2a membrane-specific untranslated region plays a major role in specifying downstream termination. We further conclude that the immunoglobulin gamma 2a, membrane-specific, 3'-untranslated region can function in the context of the gpt gene, driven by an SV40 promoter, to terminate transcription in a poly(A) site dependent fashi on.