Previous Article | Next Article ![]()
Mol. Cell. Biol., 09 1997, 5136-5145, Vol 17, No. 9
DP Eisinger, FA Dick and BL Trumpower
QSR1 is a recently discovered, essential Saccharomyces cerevisiae gene,
which encodes a 60S ribosomal subunit protein. Thirty-one unique
temperature-sensitive alleles of QSR1 were generated by regional codon
randomization within a conserved 20-amino-acid sequence of the QSR1-
encoded protein. The temperature-sensitive mutants arrest as viable, large,
unbudded cells 24 to 48 h after a shift to 37 degrees C. Polysome and
ribosomal subunit analysis by velocity gradient centrifugation of lysates
from temperature-sensitive qsr1 mutants and from cells in which Qsr1p was
depleted by down regulation of an inducible promoter revealed the presence
of half-mer polysomes and a large pool of free 60S subunits that lack
Qsr1p. In vitro subunit- joining assays and analysis of a mutant
conditional for the synthesis of Qsr1p demonstrate that 60S subunits devoid
of Qsr1p are unable to join with 40S subunits whereas 60S subunits that
contain either wild- type or mutant forms of the protein are capable of
subunit joining. The defective 60S subunits result from a reduced
association of mutant Qsr1p with 60S subunits. These results indicate that
Qsr1p is required for ribosomal subunit joining.
Copyright © 1997, American Society for Microbiology
Qsr1p, a 60S ribosomal subunit protein, is required for joining of 40S and 60S subunits
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»