Signal-sequence Trap in Mammalian and Yeast Cells: A Comparison |
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Authors: | G Galliciotti H Schneider L Wyder A Vitaliti M Wittmer M Ajmo R Klemenz |
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Institution: | (1) Department of Pathology, Division of Cancer Research, University Hospital, Schmelzbergstrasse 12, 8091 Zurich, Switzerland, CH |
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Abstract: | Membrane associated and secreted proteins are translated as precursors containing a signal peptide that allows protein-insertion
into the membrane of the endoplasmic reticulum and is co-translationally removed in the lumen. The ability of the signal peptide
to direct a polypeptide into the secretory pathway is exploited in methods developed to select cDNAs encoding such proteins.
Different strategies are known in which cDNA libraries can be screened for signal peptides by the ability of the latter to
rescue the translocation of signal sequence-less proteins. In one method, a cDNA library is tested for interleukin 2 receptor
α chain translocation to the membrane in COS cells, in another one for invertase secretion from yeast. In this work, we compared
the two systems by testing six mouse signal peptides in COS and yeast cells. All of them were functional in the mammalian
system, whereas only three of them in yeast. Two other sequences needed the 5′ cDNA sequence flanking the ATG codon to be
removed in order to enable protein translocation. Although the structure of signal sequences and the functioning of the secretory
machinery are well conserved from prokaryotes to eukaryotes, it seems evident that not all signal peptides can be interchanged
between different proteins and organisms. In particular, signal peptides that are functional in the mammalian system do not
necessarily lead to protein translocation in yeast.
Received: 9 March 2001 |
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Keywords: | : Signal sequence — Signal sequence trap — Membrane protein — Protein translocation — Yeast |
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