scholarly journals The conserved role of Smu1 in splicing is characterized in its mammalian temperature-sensitive mutant

2006 ◽  
Vol 119 (23) ◽  
pp. 4944-4951 ◽  
Author(s):  
K. Sugaya ◽  
E. Hongo ◽  
Y. Ishihara ◽  
H. Tsuji
Keyword(s):  
Temperature Sensitive ◽  
Sensitive Mutant ◽  
Temperature Sensitive Mutant

scholarly journals Bir1 Is Required for the Tension Checkpoint

2009 ◽  
Vol 20 (3) ◽  
pp. 915-923 ◽  
Author(s):  
Michelle M. Shimogawa ◽  
Per O. Widlund ◽  
Michael Riffle ◽  
Michael Ess ◽  
Trisha N. Davis
Keyword(s):  
Aurora B ◽  
Temperature Sensitive ◽  
Sensitive Mutant ◽  
Checkpoint Response ◽  
Temperature Sensitive Mutant ◽  
The Third ◽  
Chromosomal Passenger ◽  
Chromosomal Passenger Proteins ◽  
Passenger Proteins

The Saccharomyces cerevisiae chromosomal passenger proteins Ipl1 (Aurora B) and Sli15 (INCENP) are required for the tension checkpoint, but the role of the third passenger, Bir1, is controversial. We have isolated a temperature-sensitive mutant (bir1-107) in the essential C-terminal region of Bir1 known to be required for binding to Sli15. This allele reveals a checkpoint function for Bir1. The mutant displays a biorientation defect, a defective checkpoint response to lack of tension, and an inability to detach mutant kinetochores. Ipl1 localizes to aberrant foci when Bir1 localization is disrupted in the bir1-107 mutant. Thus, one checkpoint role of Bir1 is to properly localize Ipl1 and allow detachment of kinetochores. Quantitative analysis indicates that the chromosomal passengers colocalize with kinetochores in G1 but localize between kinetochores that are under tension. Bir1 localization to kinetochores is maintained in an mcd1-1 mutant in the absence of tension. Our results suggest that the establishment of tension removes Ipl1, Bir1, and Sli15, and their kinetochore detachment activity, from the vicinity of kinetochores and allows cells to proceed through the tension checkpoint.

scholarly journals Apg5p Functions in the Sequestration Step in the Cytoplasm-to-Vacuole Targeting and Macroautophagy Pathways

2000 ◽  
Vol 11 (3) ◽  
pp. 969-982 ◽  
Author(s):  
Michael D. George ◽  
Misuzu Baba ◽  
Sidney V. Scott ◽  
Noboru Mizushima ◽  
Brian S. Garrison ◽  
...  
Keyword(s):  
Biochemical Analysis ◽  
Temperature Sensitive ◽  
Vesicle Formation ◽  
Concerted Action ◽  
Sensitive Mutant ◽  
Temperature Sensitive Mutant ◽  
Dynamic Events

The cytoplasm-to-vacuole targeting (Cvt) pathway and macroautophagy are dynamic events involving the rearrangement of membrane to form a sequestering vesicle in the cytosol, which subsequently delivers its cargo to the vacuole. This process requires the concerted action of various proteins, including Apg5p. Recently, it was shown that another protein required for the import of aminopeptidase I (API) and autophagy, Apg12p, is covalently attached to Apg5p through the action of an E1-like enzyme, Apg7p. We have undertaken an analysis of Apg5p function to gain a better understanding of the role of this novel nonubiquitin conjugation reaction in these import pathways. We have generated the first temperature-sensitive mutant in the Cvt pathway, designated apg5 ts. Biochemical analysis of API import in theapg5 ts strain confirmed that Apg5p is directly required for the import of API via the Cvt pathway. By analyzing the stage of API import that is blocked in theapg5 ts mutant, we have determined that Apg5p is involved in the sequestration step and is required for vesicle formation and/or completion.

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