Elizabeth B. Keller

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The trp, phe, his, thr, and leu operons of enteric bacteria are regulated by a transcriptional attenuation mechanism. Under conditions of amino acid sufficiency, transcription terminates at an attenuator site after a leader of about 150 nucleotides has been synthesized. Under conditions of limitation of a controlling amino acid, transcription continues past(More)
The introns of Drosophila pre-mRNAs have been analysed for conserved internal sequence elements near the 3' intron boundary similar to the T-A-C-T-A-A-C in yeast introns and the C/T-T-A/G-A-C/T in introns of other organisms. Such conserved internal elements are the 3' splice signals recognized in intron splicing. In the lariat splicing mechanism, the G at(More)
Splicing of introns of yeast pre-mRNAs requires an internal conserved sequence T-A-C-T-A-A-C that is located 20-55 nucleotides from the 3' intron boundary. Sequences differing only in certain positions from this yeast signal have now been identified in the corresponding internal region of pre-mRNA introns of a variety of animal genes. A computer program(More)
DNA sequences have been determined for two actin genes which are closely linked in the genome of the sea urchin Strongylocentrotus purpuratus. The two genes have the same 5'-3' orientation; they were apparently formed originally by tandem gene duplication. The amino acids encoded by the two genes closely resemble those of cytoplasmic actins of mammals and(More)
The major cytoskeletal actin gene of Drosophila melanogaster, the actin 5C gene, has two promoters, the proximal one of which controls constitutive synthesis of actin in all growing tissues. To locate regulatory elements required for constitutive activity of the proximal promoter, mutants of this promoter were fused to the bacterial chloramphenicol(More)
Poly(A) polymerase activity was first detected in yeast extracts, primarily in association with the ribosomal fraction, by Twu and Bretthauer in 1971 (Twu, J. S., and Bretthauer, RK. (1971) Biochemistry 10, 1576-1582). This activity has now been separated into three distinct enzymes by chromatography on DEAE-cellulose. Each of the three enzymes can catalyze(More)
The promoter of the human Ha-ras gene is very GC-rich, has four Sp1-binding sites and no TATA element. Transcription initiates at multiple start sites spread over a 90-base pair region, with a major cluster between +1 and +11. We detected the binding of a HeLa nuclear protein to the region from +6 to +20, a region which overlaps the major cluster and(More)
The nucleotide sequence of the control region of the leu operon of Salmonella typhimurium was determined. A prominent feature of this region is a signal for termination of transcription. In vitro, transcription does terminate at this site, yielding a leader RNA of about 160 nucleotides as a major product. This leader RNA is potentially translatable into a(More)