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Mol. Cell. Biol., Jun 1997, 3242-3253, Vol 17, No. 6
Y Shu, H Yang, E Hallberg and R Hallberg
The Saccharomyces cerevisiae gene RTS1 encodes a protein homologous to a
variable B-type regulatory subunit of the mammalian heterotrimeric
serine/threonine protein phosphatase 2A (PP2A). We present evidence showing
that Rts1p assembles into similar heterotrimeric complexes in yeast.
Strains in which RTS1 has been disrupted are temperature sensitive (ts) for
growth, are hypersensitive to ethanol, are unable to grow with glycerol as
their only carbon source, and accumulate at nonpermissive temperatures
predominantly as large-budded cells with a 2N DNA content and a nondivided
nucleus. This cell cycle arrest can be overcome and partial suppression of
the ts phenotype of rts1-null cells occurs if the gene CLB2, encoding a
Cdc28 kinase-associated B-type cyclin, is expressed on a high-copy-number
plasmid. However, CLB2 overexpression has no suppressive effects on other
aspects of the rts1- null phenotype. Expression of truncated forms of Rts1p
can also partially suppress the ts phenotype and can fully suppress the
inability of cells to grow on glycerol and the hypersensitivity of cells to
ethanol. By contrast, the truncated forms do not suppress the accumulation
of large-budded cells at high temperatures. Coexpression of truncated Rts1p
and high levels of Clb2p fully suppresses the ts phenotype, indicating that
the inhibition of growth of rts1-null cells at high temperatures is due to
both stress-related and cell cycle- related defects. Genetic analyses show
that the role played by Rts1p in PP2A regulation is distinctly different
from that played by the other known variable B regulatory subunit, Cdc55p,
a protein recently implicated in checkpoint control regulation.
Copyright © 1997, American Society for Microbiology
Molecular genetic analysis of Rts1p, a B' regulatory subunit of Saccharomyces cerevisiae protein phosphatase 2A
Department of Biology, Syracuse University, New York 13244, USA.
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