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Mammalian Sec61 is associated with Sec62 and Sec63

Item Type:Article
Title:Mammalian Sec61 is associated with Sec62 and Sec63
Creators Name:Meyer, H.A. and Grau, H. and Kraft, R. and Kostka, S. and Prehn, S. and Kalies, K.U. and Hartmann, E.
Abstract:In yeast, efficient protein transport across the endoplasmic reticulum (ER) membrane may occur co-translationally or post-translationally. The latter process is mediated by a membrane protein complex that consists of the Sec61p complex and the Sec62p-Sec63p subcomplex. In contrast, in mammalian cells protein translocation is almost exclusively co-translational. This transport depends on the Sec61 complex, which is homologous to the yeast Sec61p complex and has been identified in mammals as a ribosome-bound pore- forming membrane protein complex. We report here the existence of ribosome- free mammalian Sec61 complexes that associate with two ubiquitous proteins of the ER membrane. According to primary sequence analysis both proteins display homology to the yeast proteins Sec62p and Sec63p and are therefore named Sec62 and Sec63, respectively. The probable function of the mammalian Sec61- Sec62-Sec63 complex is discussed with respect to its abundance in ER membranes, which, in contrast to yeast ER membranes, apparently lack efficient post-translational translocation activity.
Keywords:Amino Acid Sequence, Amino Acid Sequence Homology, Base Sequence, Biological Transport, DNA Primers, Endoplasmic Reticulum, Fungal Proteins, Heat-Shock Proteins, Membrane Proteins, Membrane Transport Proteins, Molecular Cloning, Molecular Sequence Data, Protein Binding, Post-Translational Protein Processing, Saccharomyces Cerevisiae, Saccharomyces Cerevisiae Proteins
Source:Journal of Biological Chemistry
Publisher:American Society for Biochemistry and Molecular Biology
Page Range:14550-14557
Date:12 May 2000
Official Publication:http://www.jbc.org/cgi/content/abstract/275/19/14550
PubMed:View item in PubMed

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