Showing papers on "Transcription factor published in 1977"

Specificity of the weak binding between the phage SPO1 transcription-inhibitory protein, TF1, and SPO1 DNA.

Abstract: The interaction of the phage SPO1 protein transcription factor 1 (TF1), with DNA has been analyzed by membrane filter binding and by sedimentation methods. Substantially specific binding of TF1 to helical SPO1 DNA can be demonstrated by nitrocellulose filter-binding assays at relatively low ionic strength (0.08). However, TF1-DNA complexes dissociate and reequilibrate relatively rapidly and this makes filter-binding assays unsuitable for quantitative measurements of binding equilibra. Accordingly, the sedimentation properties of TF1-DNA complexes have been explored and a short-column centrifugation assay has been elaborated for quantitative measurements. Preferential binding of TF1 to the hydroxymethyluracil-containing SPO1 DNA has also been demonstrated by short-column centrifugation. TF1 binds relatively weakly and somewhat cooperatively to SPO1 DNA at many sites; TF1-DNA complexes dissociate and reequilibrate rapidly. At 20 degrees C in 0.01 M phosphate, pH 7.5, 0.15 KC1, one molecule of TF1 can bind to approximately every 60 nucleotide pairs of SPO1 DNA.

A Nuclear Elongation Factor of Transcription from Physarum polycephalum in vitro

Abstract: Homogenates of Physarum plasmodia contain a factor which stimulates UMP incorporation on native DNA by solubilized homologous RNA polymerases in vitro. The factor is a heat-sensitive protein and has been located in nuclei. It does not alter the template activity of DNA nor the initiation frequency of transcription. The factor interacts with free or bound RNA polymerase molecules (only 37 degrees C and at low ionic strength) and yields larger transcripts in vitro. The level of the factor in vitro fluctuates: it is gradually reduced during spherulation and reaches its maximum in mid S phase of the cell cycle of Physarum.