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Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence

We have constructed a series of mutations in the signal sequence of the yeast vacuolar protein carboxypeptidase Y (CPY), and have used pulse- chase radiolabeling and immunoprecipitation to examine the in vivo effects of these mutations on the entry of the mutant CPY proteins into the secretory pathw...

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Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1987
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114485/
https://www.ncbi.nlm.nih.gov/pubmed/3032983
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collection PubMed
description We have constructed a series of mutations in the signal sequence of the yeast vacuolar protein carboxypeptidase Y (CPY), and have used pulse- chase radiolabeling and immunoprecipitation to examine the in vivo effects of these mutations on the entry of the mutant CPY proteins into the secretory pathway. We find that introduction of a negatively charged residue, aspartate, into the hydrophobic core of the signal sequence has no apparent effect on signal sequence function. In contrast, internal in-frame deletions within the signal sequence cause CPY to be synthesized as unglycosylated precursors. These are slowly and inefficiently converted to glycosylated precursors that are indistinguishable from the glycosylated forms produced from the wild- type gene. These precursors are converted to active CPY in a PEP4- dependent manner, indicating that they are correctly localized to the vacuole. Surprisingly, a deletion mutation that removes the entire CPY signal sequence has a similar effect: unglycosylated precursor accumulates in cells carrying this mutant gene, and greater than 10% of it is posttranslationally glycosylated. Thus, the amino-terminal signal sequence of CPY, while important for translocation efficiency, is not absolutely required for the translocation of this protein.
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spelling pubmed-21144852008-05-01 Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence J Cell Biol Articles We have constructed a series of mutations in the signal sequence of the yeast vacuolar protein carboxypeptidase Y (CPY), and have used pulse- chase radiolabeling and immunoprecipitation to examine the in vivo effects of these mutations on the entry of the mutant CPY proteins into the secretory pathway. We find that introduction of a negatively charged residue, aspartate, into the hydrophobic core of the signal sequence has no apparent effect on signal sequence function. In contrast, internal in-frame deletions within the signal sequence cause CPY to be synthesized as unglycosylated precursors. These are slowly and inefficiently converted to glycosylated precursors that are indistinguishable from the glycosylated forms produced from the wild- type gene. These precursors are converted to active CPY in a PEP4- dependent manner, indicating that they are correctly localized to the vacuole. Surprisingly, a deletion mutation that removes the entire CPY signal sequence has a similar effect: unglycosylated precursor accumulates in cells carrying this mutant gene, and greater than 10% of it is posttranslationally glycosylated. Thus, the amino-terminal signal sequence of CPY, while important for translocation efficiency, is not absolutely required for the translocation of this protein. The Rockefeller University Press 1987-05-01 /pmc/articles/PMC2114485/ /pubmed/3032983 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence
title Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence
title_full Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence
title_fullStr Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence
title_full_unstemmed Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence
title_short Yeast carboxypeptidase Y can be translocated and glycosylated without its amino-terminal signal sequence
title_sort yeast carboxypeptidase y can be translocated and glycosylated without its amino-terminal signal sequence
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114485/
https://www.ncbi.nlm.nih.gov/pubmed/3032983