scholarly journals Co-operation between different targeting pathways during integration of a membrane protein

2012 ◽  
Vol 199 (2) ◽  
pp. 303-315 ◽  
Author(s):  
Rebecca Keller ◽  
Jeanine de Keyzer ◽  
Arnold J.M. Driessen ◽  
Tracy Palmer
Keyword(s):  
Membrane Protein ◽  
Protein Transport ◽  
Transmembrane Domain ◽  
Energy Coupling ◽  
Integral Membrane Protein ◽  
Transmembrane Domains ◽  
Dependent Manner ◽  
Rieske Protein ◽  
Transport Pathway ◽  
Iron Sulfur

Membrane protein assembly is a fundamental process in all cells. The membrane-bound Rieske iron-sulfur protein is an essential component of the cytochrome bc1 and cytochrome b6f complexes, and it is exported across the energy-coupling membranes of bacteria and plants in a folded conformation by the twin arginine protein transport pathway (Tat) transport pathway. Although the Rieske protein in most organisms is a monotopic membrane protein, in actinobacteria, it is a polytopic protein with three transmembrane domains. In this work, we show that the Rieske protein of Streptomyces coelicolor requires both the Sec and the Tat pathways for its assembly. Genetic and biochemical approaches revealed that the initial two transmembrane domains were integrated into the membrane in a Sec-dependent manner, whereas integration of the third transmembrane domain, and thus the correct orientation of the iron-sulfur domain, required the activity of the Tat translocase. This work reveals an unprecedented co-operation between the mechanistically distinct Sec and Tat systems in the assembly of a single integral membrane protein.

scholarly journals A Novel Golgi Membrane Protein Is a Partner of the ARF Exchange Factors Gea1p and Gea2p

2003 ◽  
Vol 14 (6) ◽  
pp. 2357-2371 ◽  
Author(s):  
Sophie Chantalat ◽  
Rëgis Courbeyrette ◽  
Francesca Senic-Matuglia ◽  
Catherine L. Jackson ◽  
Bruno Goud ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Trafficking ◽  
Transmembrane Domain ◽  
Integral Membrane Protein ◽  
Membrane Dynamics ◽  
General Interest ◽  
Single Mutation ◽  
Golgi Membrane ◽  
Nucleotide Exchange

The Sec7 domain guanine nucleotide exchange factors (GEFs) for the GTPase ARF are highly conserved regulators of membrane dynamics and protein trafficking. The interactions of large ARF GEFs with cellular membranes for localization and/or activation are likely to participate in regulated recruitment of ARF and effectors. However, these interactions remain largely unknown. Here we characterize Gmh1p, the first Golgi transmembrane-domain partner of any of the high-molecular-weight ARF-GEFs. Gmh1p is an evolutionarily conserved protein. We demonstrate molecular interaction between the yeast Gmh1p and the large ARF-GEFs Gea1p and Gea2p. This interaction involves a domain of Gea1p and Gea2p that is conserved in the eukaryotic orthologues of the Gea proteins. A single mutation in a conserved amino acid residue of this domain is sufficient to abrogate the interaction, whereas the overexpression of Gmh1p can compensate in vivo defects caused by mutations in this domain. We show that Gmh1p is an integral membrane protein that localizes to the early Golgi in yeast and in human HeLa cells and cycles through the ER. Hence, we propose that Gmh1p acts as a positive Golgi-membrane partner for Gea function. These results are of general interest given the evolutionary conservation of both ARF-GEFs and the Gmh proteins.

scholarly journals Characterization of YmgF, a 72-Residue Inner Membrane Protein That Associates with the Escherichia coli Cell Division Machinery

2008 ◽  
Vol 191 (1) ◽  
pp. 333-346 ◽  
Author(s):  
Gouzel Karimova ◽  
Carine Robichon ◽  
Daniel Ladant
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Membrane Protein ◽  
Integral Membrane Protein ◽  
Dependent Manner ◽  
E Coli ◽  
Division Site ◽  
Inner Membrane Protein ◽  
Two Hybrid

ABSTRACT Formation of the Escherichia coli division septum is catalyzed by a number of essential proteins (named Fts) that assemble into a ring-like structure at the future division site. Many of these Fts proteins are intrinsic transmembrane proteins whose functions are largely unknown. In the present study, we attempted to identify a novel putative component(s) of the E. coli cell division machinery by searching for proteins that could interact with known Fts proteins. To do that, we used a bacterial two-hybrid system based on interaction-mediated reconstitution of a cyclic AMP (cAMP) signaling cascade to perform a library screening in order to find putative partners of E. coli cell division protein FtsL. Here we report the characterization of YmgF, a 72-residue integral membrane protein of unknown function that was found to associate with many E. coli cell division proteins and to localize to the E. coli division septum in an FtsZ-, FtsA-, FtsQ-, and FtsN-dependent manner. Although YmgF was previously shown to be not essential for cell viability, we found that when overexpressed, YmgF was able to overcome the thermosensitive phenotype of the ftsQ1(Ts) mutation and restore its viability under low-osmolarity conditions. Our results suggest that YmgF might be a novel component of the E. coli cell division machinery.

scholarly journals Epithelial membrane glycoprotein PAS-IV is related to platelet glycoprotein IIIb binding to thrombospondin but not to malaria-infected erythrocytes

Blood ◽  
1991 ◽  
Vol 77 (12) ◽  
pp. 2649-2654 ◽  
Author(s):  
B Catimel ◽  
JL McGregor ◽  
T Hasler ◽  
DE Greenwalt ◽  
RJ Howard ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Mammary Epithelial Cells ◽  
Integral Membrane Protein ◽  
Mammary Epithelial ◽  
Platelet Glycoprotein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Protein Receptors ◽  
Capillary Endothelial Cells ◽  
Peptide Map

Abstract Glycoprotein (GP) IIIb (also termed GPIV or CD36) is an integral platelet membrane protein, and has been identified as a binding site for thrombospondin, collagen, and malaria-infected erythrocytes. PAS-IV is an integral membrane protein found in lactating mammary epithelial cells and capillary endothelial cells. The N-terminal sequence of PAS- IV is nearly identical to that of GPIIIb and monospecific anti-PAS-IV antibody reacts with GPIIIb, indicating that PAS-IV is structurally related to GPIIIb. In this study, human platelet GPIIIb and bovine epithelial PAS-IV were compared in terms of structural, immunologic, and functional characteristics. The two-dimensional tryptic peptide map of both intact and deglycosylated PAS-IV was highly similar but not identical to that of GPIIIb. PAS-IV and GPIIIb reacted to an equal extent with monoclonal antibodies OKM5 and OKM8 by enzyme-linked immunosorbent assay. GPIIIb bound to surface immobilized thrombospondin (TSP) in a concentration-dependent and saturable manner, with approximately 60% reduction in binding in the presence of EDTA. PAS-IV bound to TSP with similar characteristics except that maximum binding was consistently approximately 50% of that of GPIIIb and binding was not inhibited by EDTA. GPIIIb supported adhesion of Plasmodium falciparum-infected erythrocytes (PRBC) in a dose-dependent manner while no significant adhesion of PRBC to PAS-IV was observed. Our data demonstrate that while epithelial PAS-IV and platelet GPIIIb are structurally and immunologically related, there are significant differences in their functional properties. Whether this result is due to different posttranslational glycosylation modifications or that PAS- IV and GPIIIb represent a family of related cell adhesive protein receptors remains to be determined.

The amino-terminal 14 amino acids of v-src can functionally replace the extracellular and transmembrane domains of v-erbB

1991 ◽  
Vol 11 (9) ◽  
pp. 4760-4770
Author(s):  
M McMahon ◽  
R C Schatzman ◽  
J M Bishop
Keyword(s):  
Membrane Protein ◽  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Transmembrane Domain ◽  
Transmembrane Protein ◽  
Integral Membrane Protein ◽  
Kinase Domain ◽  
Protein Tyrosine ◽  
Amino Terminal ◽  
Transforming Activity

The retroviral oncogene v-erbB encodes a truncated form of the receptor for epidermal growth factor, an integral membrane protein-tyrosine kinase. By contrast, the oncogene v-src encodes a protein-tyrosine kinase that is a peripheral membrane protein. The morphologies and spectra of cells transformed by these two oncogenes differ. In an effort to identify the functional determinant(s) of these differences, we constructed and tested first deletion mutants of v-erbB and then chimeras between v-src and v-erbB. As reported previously, the absence of any membrane anchorage eliminated transformation by v-erbB. Anchorage of the cytoplasmic kinase domain of v-erbB to membranes with amino-terminal portions of the v-src protein permitted transformation. The phenotype and spectrum of transformation were those expected for v-erbB rather than for v-src. The transforming chimeras lost their biological activity if the signal for myristylation at the amino terminus of v-src was compromised by mutation. Biochemical fractionations revealed a correlation between transforming activity and the association of chimeric gene products with the membrane fraction of the cell. For reasons not yet apparent, the combined presence of membrane anchorage domains of v-src, and the transmembrane domain of v-erbB in the same chimera typically (but not inevitably) impeded transformation. Our results suggest that the specificity of transformation by v-erbB resides in the selection of substrates by the cytoplasmic domain of the gene product. The protein retains access to those substrates even when anchored to the membrane in the manner of a peripheral rather than a transmembrane protein.

scholarly journals Epithelial membrane glycoprotein PAS-IV is related to platelet glycoprotein IIIb binding to thrombospondin but not to malaria-infected erythrocytes

Blood ◽  
1991 ◽  
Vol 77 (12) ◽  
pp. 2649-2654
Author(s):  
B Catimel ◽  
JL McGregor ◽  
T Hasler ◽  
DE Greenwalt ◽  
RJ Howard ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Mammary Epithelial Cells ◽  
Integral Membrane Protein ◽  
Mammary Epithelial ◽  
Platelet Glycoprotein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Protein Receptors ◽  
Capillary Endothelial Cells ◽  
Peptide Map

Glycoprotein (GP) IIIb (also termed GPIV or CD36) is an integral platelet membrane protein, and has been identified as a binding site for thrombospondin, collagen, and malaria-infected erythrocytes. PAS-IV is an integral membrane protein found in lactating mammary epithelial cells and capillary endothelial cells. The N-terminal sequence of PAS- IV is nearly identical to that of GPIIIb and monospecific anti-PAS-IV antibody reacts with GPIIIb, indicating that PAS-IV is structurally related to GPIIIb. In this study, human platelet GPIIIb and bovine epithelial PAS-IV were compared in terms of structural, immunologic, and functional characteristics. The two-dimensional tryptic peptide map of both intact and deglycosylated PAS-IV was highly similar but not identical to that of GPIIIb. PAS-IV and GPIIIb reacted to an equal extent with monoclonal antibodies OKM5 and OKM8 by enzyme-linked immunosorbent assay. GPIIIb bound to surface immobilized thrombospondin (TSP) in a concentration-dependent and saturable manner, with approximately 60% reduction in binding in the presence of EDTA. PAS-IV bound to TSP with similar characteristics except that maximum binding was consistently approximately 50% of that of GPIIIb and binding was not inhibited by EDTA. GPIIIb supported adhesion of Plasmodium falciparum-infected erythrocytes (PRBC) in a dose-dependent manner while no significant adhesion of PRBC to PAS-IV was observed. Our data demonstrate that while epithelial PAS-IV and platelet GPIIIb are structurally and immunologically related, there are significant differences in their functional properties. Whether this result is due to different posttranslational glycosylation modifications or that PAS- IV and GPIIIb represent a family of related cell adhesive protein receptors remains to be determined.

scholarly journals Thylakoid-integrated recombinant Hcf106 participates in the chloroplast Twin Arginine Transport (cpTat) system

2018 ◽  
Author(s):  
Qianqian Ma ◽  
Kristen Fite ◽  
Christopher Paul New ◽  
Carole Dabney-Smith
Keyword(s):  
Protein Transport ◽  
Transmembrane Domain ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sole Source ◽  
Receptor Complex ◽  
Amphipathic Helix ◽  
Transport Pathway ◽  
Independent Manner ◽  
Arginine Transport

AbstractThe chloroplast Twin arginine transport (cpTat) system distinguishes itself as a protein transport pathway by translocating fully-folded proteins, using the proton-motive force (PMF) as the sole source of energy. The cpTat pathway is evolutionarily conserved with the Tat pathway found in the plasma membrane of many prokaryotes. The cpTat (E. coli) system uses three proteins, Tha4 (TatA), Hcf106 (TatB), and cpTatC (TatC), to form a transient translocase allowing the passage of precursor proteins. Briefly, cpTatC and Hcf106, with Tha4, form the initial receptor complex responsible for precursor protein recognition and binding in an energy-independent manner, while a separate pool of Tha4 assembles with the precursor-bound receptor complex in the presence the PMF. Analysis by blue-native polyacrylamide gel electrophoresis (BN-PAGE) shows that the receptor complex, in the absence of precursor, migrates near 700 kDa and contains cpTatC and Hcf106 with little Tha4 remaining after detergent solubilization. To investigate the role that Hcf106 may play in receptor complex oligomerization and/or stability, systematic cysteine substitutions were made in positions from the N-terminal transmembrane domain to the end of the predicted amphipathic helix of the protein. BN-PAGE analysis allowed us to identify the locations of amino acids in Hcf106 that were critical for interacting with cpTatC. Oxidative cross-linking allowed us to map interactions of the transmembrane domain and amphipathic helix region of Hcf106. In addition, we showed that in vitro expressed, integrated Hcf106 can interact with the precursor signal peptide domain and imported cpTatC, strongly suggesting that a subpopulation of the integrated Hcf106 is participating in competent cpTat complexes.

scholarly journals Juxta-membrane S-acylation of plant receptor-like kinases – fortuitous or functional?

2019 ◽  
Author(s):  
Charlotte H. Hurst ◽  
Kathryn M. Wright ◽  
Dionne Turnbull ◽  
Kerry Leslie ◽  
Susan Jones ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Substrate Specificity ◽  
Plant Pathogen ◽  
Transmembrane Domain ◽  
Transmembrane Domains ◽  
Cysteine Residues ◽  
Post Translational Modification ◽  
Receptor Like Kinase ◽  
Protein Properties

AbstractS-acylation is a common post-translational modification of membrane protein cysteine residues with many regulatory roles. S-acylation adjacent to transmembrane domains has been described in the literature as affecting diverse protein properties including turnover, trafficking and microdomain partitioning. However, all of these data are derived from mammalian and yeast systems. Here we examine the role of S-acylation adjacent to the transmembrane domain of the plant pathogen perceiving receptor-like kinase FLS2. Surprisingly, S-acylation of FLS2 adjacent to the transmembrane domain is not required for either FLS2 trafficking or signalling function. Expanding this analysis to the wider plant receptor-like kinase superfamily we find that S-acylation adjacent to receptor-like kinase domains is common but poorly conserved between orthologues through evolution. This suggests that S-acylation of receptor-like kinases at this site is likely the result of chance mutation leading to cysteine occurrence. As transmembrane domains followed by cysteine residues are common motifs for S-acylation to occur, and many S-acyl transferases appear to have lax substrate specificity, we propose that many receptor-like kinases are fortuitously S-acylated once chance mutation has introduced a cysteine at this site. Interestingly some receptor-like kinases show conservation of S-acylation sites between orthologues suggesting that S-acylation has come to play a role and has been positively selected for during evolution. The most notable example of this is in the ERECTA-like family where S-acylation of ERECTA adjacent to the transmembrane domain occurs in all ERECTA orthologues but not in the parental ERECTA-like clade. This suggests that ERECTA S-acylation occurred when ERECTA emerged during the evolution of angiosperms and may have contributed to the neo-functionalisation of ERECTA from ERECTA-like proteins.

scholarly journals Localization and targeting of the Saccharomyces cerevisiae Kre2p/Mnt1p alpha 1,2-mannosyltransferase to a medial-Golgi compartment.

1995 ◽  
Vol 131 (4) ◽  
pp. 913-927 ◽  
Author(s):  
M Lussier ◽  
A M Sdicu ◽  
T Ketela ◽  
H Bussey
Keyword(s):  
Membrane Protein ◽  
Transmembrane Domain ◽  
Glycosylation Site ◽  
Dependent Manner ◽  
Reporter Protein ◽  
Golgi Localization ◽  
Golgi Compartment ◽  
Membrane Spanning

The yeast Kre2p/Mnt1p alpha 1,2-mannosyltransferase is a type II membrane protein with a short cytoplasmic amino terminus, a membrane-spanning region, and a large catalytic luminal domain containing one N-glycosylation site. Anti-Kre2p/Mnt1p antibodies identify a 60-kD integral membrane protein that is progressively N-glycosylated in an MNN1-dependent manner. Kre2p/Mnt1p is localized in a Golgi compartment that overlaps with that containing the medial-Golgi mannosyltransferase Mnn1p, and distinct from that including the late Golgi protein Kex1p. To determine which regions of Kre2p/Mnt1p are required for Golgi localization, Kre2p/Mnt1p mutant proteins were assembled by substitution of Kre2p domains with equivalent sequences from the vacuolar proteins DPAP B and Pho8p. Chimeric proteins were tested for correct topology, in vitro and in vivo activity, and were localized intracellularly by indirect immunofluorescence. The results demonstrate that the NH2-terminal cytoplasmic domain is necessary for correct Kre2p Golgi localization whereas, the membrane-spanning and stem domains are dispensable. However, in a test of targeting sufficiency, the presence of the entire Kre2p cytoplasmic tail, plus the transmembrane domain and a 36-amino acid residue luminal stem region was required to localize a Pho8p reporter protein to the yeast Golgi.

scholarly journals The 17-residue transmembrane domain of beta-galactoside alpha 2,6-sialyltransferase is sufficient for Golgi retention

1992 ◽  
Vol 117 (2) ◽  
pp. 245-258 ◽  
Author(s):  
SH Wong ◽  
SH Low ◽  
W Hong
Keyword(s):  
Golgi Apparatus ◽  
Membrane Protein ◽  
Transmembrane Domain ◽  
Integral Membrane Protein ◽  
Chimeric Proteins ◽  
Type Ii ◽  
Lectin Affinity Chromatography ◽  
Golgi Retention ◽  
A Cell ◽  
Golgi Network

beta-Galactoside alpha 2,6-sialyltransferase (ST) is a type II integral membrane protein of the Golgi apparatus involved in the sialylation of N-linked glycans. A series of experiments has shown that the 17-residue transmembrane domain of ST is sufficient to confer localization to the Golgi apparatus when transferred to the corresponding region of a cell surface type II integral membrane protein. Lectin affinity chromatography of chimeric proteins bearing this 17-residue sequence suggests that these chimeric proteins are localized in the trans-Golgi cisternae and/or trans-Golgi network. Further experiments suggest that this 17-residue sequence functions as a retention signal for the Golgi apparatus.

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