E

Berg, H.F. van den; Fähnders, Walter

doi:10.1007/978-3-476-05202-5_6

Cited by 4 publications

(6 citation statements)

References 4 publications

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“…The crystal structure of an archaeal SecY complex provides much insight into channel function [2]. The structure is likely representative of all species, as indicated by sequence conservation and by the similarity to a lower resolution structure of the Escherichia coli SecY complex determined by electron microscopy (EM) from 2D crystals [12].…”

Section: Structure and Function Of The Translocation Channelmentioning

confidence: 99%

“…The crystal structure indicates that a single copy of the Sec61 ⁄ SecY complex forms the pore [2]. The translocation of a secretory protein begins with insertion of a loop into the channel, such that the signal sequence is intercalated into the walls of the channel and the segment distal to it is inserted into the pore proper (Figs 1-3 .…”

Section: Opening the Channel Across The Membranementioning

confidence: 99%

“…Structural and biochemical data suggest mechanisms that enable the channel to function with different partners, to open across the membrane and to release laterally hydrophobic segments of membrane proteins into lipid. complex, called the Sec61 complex in eukaryotes and the SecY complex in bacteria and archaea [2]. The a-subunit forms the channel pore, as originally demonstrated by systematic crosslinking experiments [3].…”

Section: Introductionmentioning

confidence: 99%

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Protein transport across the endoplasmic reticulum membrane

Rapoport

2008

The FEBS Journal

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A decisive step in the biosynthesis of many eukaryotic proteins is their partial or complete translocation across the endoplasmic reticulum membrane. A similar process occurs in prokaryotes, except that proteins are transported across or are integrated into the plasma membrane. In both cases, translocation occurs through a protein‐conducting channel that is formed from a conserved, heterotrimeric membrane protein complex, the Sec61 or SecY complex. Structural and biochemical data suggest mechanisms that enable the channel to function with different partners, to open across the membrane and to release laterally hydrophobic segments of membrane proteins into lipid.

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Section: Structure and Function Of The Translocation Channelmentioning

confidence: 99%

Section: Opening the Channel Across The Membranementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Protein transport across the endoplasmic reticulum membrane

Rapoport

2008

The FEBS Journal

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“…In bacteria and archaea two general pathways mediate the export of proteins across the cytoplasmic membrane. The Sec pathway, which is the predominant route of protein export in most prokaryotes, uses a threading mechanism to transport unfolded proteins (Van den Berg et al, 2004;Driessen and Nouwen, 2008). The twin arginine transport (Tat) pathway, by contrast, exports folded proteins (reviewed in Cline and Theg, 2007;Frobel et al, 2012;Palmer and Berks, 2012).…”

Section: Introductionmentioning

confidence: 99%

Molecular dissection of TatC defines critical regions essential for protein transport and a TatB–TatC contact site

Kneuper

Maldonado

Jäger

et al. 2012

Molecular Microbiology

105

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The twin arginine transport (Tat) system transports folded proteins across the prokaryotic cytoplasmic membrane and the plant thylakoid membrane. TatC is the largest and most conserved component of the Tat machinery. It forms a multisubunit complex with TatB and binds the signal peptides of Tat substrates. Here we have taken a random mutagenesis approach to identify substitutions in Escherichia coli TatC that inactivate protein transport. We identify 32 individual amino acid substitutions that abolish or severely compromise TatC activity. The majority of the inactivating substitutions fall within the first two periplasmic loops of TatC. These regions are predicted to have conserved secondary structure and results of extensive amino acid insertion and deletion mutagenesis are consistent with these conserved elements being essential for TatC function. Three inactivating substitutions were identified in the fifth transmembrane helix of TatC. The inactive M205R variant could be suppressed by mutations affecting amino acids in the transmembrane helix of TatB. A physical interaction between TatC helix 5 and the TatB transmembrane helix was confirmed by the formation of a site-specific disulphide bond between TatC M205C and TatB L9C variants. This is the first molecular contact site mapped to single amino acid level between these two proteins.

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“…All the algorithms were implemented in Matlab 8.5 (R2015a) and performed on Intel Core i5 at 2.9 GHz and CPU 8GB 1867 MHz DDR3 memory. The Haar matrix W is generated by using Spot-A Linear-Operator Toolbox [33]. The number of scales for the wavelet transform is set equal to 3 (see Figure 3).…”

Section: Algorithm Parametersmentioning

confidence: 99%

Controlled wavelet domain sparsity for x-ray tomography

Purisha

Rimpeläinen

Bubba

et al. 2017

Meas. Sci. Technol.

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Tomographic reconstruction is an ill-posed inverse problem that calls for regularization. One possibility is to require sparsity of the unknown in an orthonormal wavelet basis. This, in turn, can be achieved by variational regularization, where the penalty term is the sum of the absolute values of the wavelet coefficients. The primal-dual fixed point (PDFP) algorithm introduced by Peijun Chen, Jianguo Huang, and Xiaoqun Zhang (Fixed Point Theory and Applications 2016) showed that the minimizer of the variational regularization functional can be computed iteratively using a soft-thresholding operation. Choosing the soft-thresholding parameter µ > 0 is analogous to the notoriously difficult problem of picking the optimal regularization parameter in Tikhonov regularization. Here, a novel automatic method is introduced for choosing µ, based on a control algorithm driving the sparsity of the reconstruction to an a priori known ratio of nonzero versus zero wavelet coefficients in the unknown.

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E

Cited by 4 publications

References 4 publications

Protein transport across the endoplasmic reticulum membrane

Protein transport across the endoplasmic reticulum membrane

Molecular dissection of TatC defines critical regions essential for protein transport and a TatB–TatC contact site

Controlled wavelet domain sparsity for x-ray tomography

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