ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Aurintricarboxilic acid as a tool for investigating the template-bound and unbound forms of RNA polymerase I in permeabilized cells (1983)

Iapalucci-Espinoza, Silvia ; Haim, Liliana ; Franze-Fernández, Maria T.

Springer

Molecular and cellular biochemistry 55 (1983), S. 41-47

add to mindlist on the mindlist

Details

ISSN: 1573-4919

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology , Medicine

Notes: Summary The presence of template-bound and unbound RNA polymerase I in permeabilized cells was investigated. The two enzyme forms were defined on the basis of their different susceptibilities towards aurintricarboxilic acid (ATA). It was found that addition of ATA to permeabilized cells suppresses initiation of new RNA chains by RNA polymerase I but has no effect on the activity of the enzyme already engaged in transcription. This last activity is not affected even after washing the permeabilized cells for removal of the ATA. The RNA polymerase I activity solubilized from permeabilized cells pre-treated with ATA is 60–70% of that obtained from non-treated controls. The decrease of the solubilized enzyme activity was observed after purification of the enzymes by DEAE-Sephadex columns and cannot be attributed to the presence of inhibitory or activating factors in the enzyme preparations. The simplest interpretation of these findings is that two distinct RNA polymerase I fractions, showing different sensitivities towards ATA are present in permeabilized cells. These fractions should represent the template-bound and unbound RNA polymerase I. The results also show that the amount of ATA-insensitive activity is lower in nuclei than in permeabilized cells, suggesting that detachment of template-bound enzyme occurs during nuclei isolation.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00229241

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Transcription of ribosomal RNA is differentially controlled in resting and growing BALB/c 3T3 cells (1985)

Perrone-Bizzozero, Nora ; Iapalucci-Espinoza, Silvia ; Medrano, Estela E. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 124 (1985), S. 160-164

add to mindlist on the mindlist

Details

ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Shortly after serum-deprived BALB/c 3T3 fibroblasts are stimulated to grow in medium containing 10% calf serum, the RNA polymerase I activity in permeabilized cells shows a two-fold increase over the values observed in either serum-deprived or density-inhibited resting cells. Inhibition of protein synthesis by pactamycin or cycloheximide specifically reduces the enhanced RNA polymerase I activity in serum-stimulated cultures without affecting the values in resting cells. On the other hand, inhibition of rRNA processing by the nucleoside analogs 5-fluoruridine and toyocamycin decreases the rate of 45S rRNA transcription in serum-stimulated cells but has no effect on the values found in resting cultures. These data suggest that the regulation of rRNA transcription occurs by two different mechanisms, depending on the growth state of the cell. One mechanism, in serum-stimulated cells, is dependent on a continuous protein synthesis and a correct 45S rRNA processing; the other, in resting cells, is independent of these two parameters.

Additional Material: 2 Ill.