scholarly journals Nucleus-specific and temporally restricted localization of proteins in Tetrahymena macronuclei and micronuclei.

1989 ◽  
Vol 109 (5) ◽  
pp. 1983-1992 ◽  
Author(s):  
E M White ◽  
C D Allis ◽  
D S Goldfarb ◽  
A Srivastva ◽  
J W Weir ◽  
...  

Labeled nuclear proteins were microinjected into the cytoplasm of Tetrahymena thermophila. Macronuclear H1, calf thymus H1, and the SV40 large T antigen nuclear localization signal linked to BSA accumulated specifically in macronuclei, even if cells were in micronuclear S phase or were nonreplicating. The way in which histone H4 localized to either the macronucleus or the micronucleus suggested that it accumulates in whichever nucleus is replicating. The inability of the micronucleus to accumulate Tetrahymena H1 or heterologous nuclear proteins, even at a period in the cell cycle when it is accumulating H4, suggests that it has a specialized transport system. These studies demonstrate that although the mechanism for localizing proteins to nuclei is highly conserved among eukaryotes, it can differ between two porecontaining nuclei lying in the same cytoplasm.

1996 ◽  
Vol 39 (5) ◽  
pp. 855-862 ◽  
Author(s):  
Yoshinari Takasaki ◽  
Tetsuro Yano ◽  
Kaoru Hirokawa ◽  
Ken Takeuchi ◽  
Soichiro Ando ◽  
...  

1988 ◽  
Vol 91 (2) ◽  
pp. 295-302
Author(s):  
A. Okuda ◽  
G. Kimura

Partial inhibition of protein synthesis by cycloheximide caused prolongation of G1, S and G2 phases in rat 3Y1 fibroblasts. In cells expressing simian virus 40 (SV40) large T antigen, by infection with SV40 in the previous generation, the prolongation of G1 phase in the presence of cycloheximide was suppressed. However, the prolongation of S and G2 phases in the presence of cycloheximide was not suppressed in cells expressing large T antigen, by infection with SV40 in the current generation. Similarly, when density-arrested cells (cells in G0 phase) were infected with SV40 (either wild-type strain or a mutant deleted in the unique coding region for small t antigen) and reseeded sparsely in the presence of cycloheximide, the cycloheximide-induced delay of entry into S phase was suppressed. In this case, the reduction in [35S]methionine incorporation, that in protein accumulation and that in cell volume increase, were not surmounted by SV40 infection. In T-antigen-negative cells, all the regions in G1 phase seemed to be sensitive to cycloheximide, i.e. they suffered elongation. These results suggest that, in comparison with cells that enter S phase by the action of growth factors, cells expressing large T antigen can enter S phase more efficiently through a quite different process.


1999 ◽  
Vol 44 (10) ◽  
pp. 823-834 ◽  
Author(s):  
M.H. Parkar ◽  
L. Kuru ◽  
M. O’Hare ◽  
H.N. Newman ◽  
F. Hughes ◽  
...  

Cell ◽  
1987 ◽  
Vol 48 (2) ◽  
pp. 321-330 ◽  
Author(s):  
Ilan Bikel ◽  
Ximena Montano ◽  
Mounzer E. Agha ◽  
Myles Brown ◽  
Melissa McCormack ◽  
...  

1986 ◽  
Vol 6 (4) ◽  
pp. 1204-1217
Author(s):  
P S Jat ◽  
C L Cepko ◽  
R C Mulligan ◽  
P A Sharp

We used a murine retrovirus shuttle vector system to construct recombinants capable of constitutively expressing the simian virus 40 (SV40) large T antigen and the polyomavirus large and middle T antigens as well as resistance to G418. Subsequently, these recombinants were used to generate cell lines that produced defective helper-free retroviruses carrying each of the viral oncogenes. These recombinant retroviruses were used to analyze the role of the viral genes in transformation of rat F111 cells. Expression of the polyomavirus middle T antigen alone resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were unaltered by the criteria of morphology, anchorage-independent growth, and tumorigenicity. More surprisingly, SV40 large T-expressing cell lines were not tumorigenic despite the fact that they contained elevated levels of cellular p53 and had a high plating efficiency in soft agar. These results suggest that the SV40 large T antigen is not an acute transforming gene like the polyomavirus middle T antigen but is similar to the establishment genes such as myc and adenovirus EIa.


1995 ◽  
Vol 217 (1) ◽  
pp. 100-108 ◽  
Author(s):  
Sharon A. King ◽  
Sandra J. Wilson ◽  
Rosann A. Farber ◽  
William K. Kaufmann ◽  
Marila Cordeiro-Stone

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