Anke Prinz, Enno Hartmann, Kai-Uwe Kalies
Sec61p Is the Main Ribosome Receptor in the Endoplasmic Reticulum of Saccharomyces cerevisiae
A characteristic feature of the co-translational protein
translocation into the endoplasmic reticulum (ER) is
the tight association of the translating ribosomes with
the translocation sites in the membrane. Biochemical
analyses identified the Sec61 complex as the main
ribosome receptor in the ER of mammalian cells. Similar
experiments using purified homologues from the
yeast Saccharomyces cerevisiae, the Sec61p complex
and the Ssh1p complex, respectively, demonstrated
that they bind ribosomes with an affinity similar to that
of the mammalian Sec61 complex. However, these
studies did not exclude the presence of other proteins
that may form abundant ribosome binding sites in the
yeast ER. We now show here that similar to the situation
found in mammals in the yeast Saccharomyces
cerevisiae the two Sec61-homologues Sec61p and
Ssh1p are essential for the formation of high-affinity
ribosome binding sites in the ER membrane. The number
of binding sites formed by Ssh1p under standard
growth conditions is at least 4 times less than those
formed by Sec61p.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 381, 09/2000
Pages: 1025 - 1028
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