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The signal recognition particle receptor is a complex that contains two distinct polypeptide chains
Signal recognition particle (SRP) and SRP receptor are known to be essential components of the cellular machinery that targets nascent secretory proteins to the endoplasmic reticulum (ER) membrane. Here we report that the SRP receptor contains, in addition to the previously identified and sequenced...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1986
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114348/ https://www.ncbi.nlm.nih.gov/pubmed/3021779 |
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collection | PubMed |
description | Signal recognition particle (SRP) and SRP receptor are known to be essential components of the cellular machinery that targets nascent secretory proteins to the endoplasmic reticulum (ER) membrane. Here we report that the SRP receptor contains, in addition to the previously identified and sequenced 69-kD polypeptide (alpha-subunit, SR alpha), a 30-kD beta-subunit (SR beta). When SRP receptor was purified by SRP- Sepharose affinity chromatography, we observed the co-purification of two other ER membrane proteins. Both proteins are approximately 30 kD in size and are immunologically distinct from each other, as well as from SR alpha and SRP proteins. One of the 30-kD proteins (SR beta) forms a tight complex with SR alpha in detergent solution that is stable to high salt and can be immunoprecipitated with antibodies to either SR alpha or SR beta. Both subunits are present in the ER membrane in equimolar amounts and co-fractionate in constant stoichiometry when rough and smooth liver microsomes are separated on sucrose gradients. We therefore conclude that SR beta is an integral component of SRP receptor. The presence of SR beta was previously masked by proteolytic breakdown products of SR alpha observed by others and by the presence of another 30-kD ER membrane protein (mp30) which co-purifies with SR alpha. Mp30 binds to SRP-Sepharose directly and is present in the ER membrane in several-fold molar excess of SR alpha and SR beta. The affinity of mp30 for SRP suggests that it may serve a yet unknown function in protein translocation. |
format | Text |
id | pubmed-2114348 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1986 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-21143482008-05-01 The signal recognition particle receptor is a complex that contains two distinct polypeptide chains J Cell Biol Articles Signal recognition particle (SRP) and SRP receptor are known to be essential components of the cellular machinery that targets nascent secretory proteins to the endoplasmic reticulum (ER) membrane. Here we report that the SRP receptor contains, in addition to the previously identified and sequenced 69-kD polypeptide (alpha-subunit, SR alpha), a 30-kD beta-subunit (SR beta). When SRP receptor was purified by SRP- Sepharose affinity chromatography, we observed the co-purification of two other ER membrane proteins. Both proteins are approximately 30 kD in size and are immunologically distinct from each other, as well as from SR alpha and SRP proteins. One of the 30-kD proteins (SR beta) forms a tight complex with SR alpha in detergent solution that is stable to high salt and can be immunoprecipitated with antibodies to either SR alpha or SR beta. Both subunits are present in the ER membrane in equimolar amounts and co-fractionate in constant stoichiometry when rough and smooth liver microsomes are separated on sucrose gradients. We therefore conclude that SR beta is an integral component of SRP receptor. The presence of SR beta was previously masked by proteolytic breakdown products of SR alpha observed by others and by the presence of another 30-kD ER membrane protein (mp30) which co-purifies with SR alpha. Mp30 binds to SRP-Sepharose directly and is present in the ER membrane in several-fold molar excess of SR alpha and SR beta. The affinity of mp30 for SRP suggests that it may serve a yet unknown function in protein translocation. The Rockefeller University Press 1986-10-01 /pmc/articles/PMC2114348/ /pubmed/3021779 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 The signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
title | The signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
title_full | The signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
title_fullStr | The signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
title_full_unstemmed | The signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
title_short | The signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
title_sort | signal recognition particle receptor is a complex that contains two distinct polypeptide chains |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114348/ https://www.ncbi.nlm.nih.gov/pubmed/3021779 |