scholarly journals A Survey of Membrane Proteins in Human Serum

2012 ◽  
Vol 5 ◽  
pp. PRI.S9374 ◽  
Author(s):  
Nguyen Tien Dung ◽  
Phan Van Chi
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Human Serum ◽  
Transmembrane Domain ◽  
Tissue Sample ◽  
Ionization Mass ◽  
Post Translational Modifications ◽  
Molecular Weights ◽  
Normal Human ◽  
Nano Liquid Chromatography

Serum and membrane proteins are two of the most attractive targets for proteomic analysis. Previous membrane protein studies tend to focus on tissue sample, while membrane protein studies in serum are still limited. In this study, an analysis of membrane proteins in normal human serum was carried out. Nano-liquid chromatography-electrospray ionization mass spectrometry (NanoLC-ESI-MS/MS) and bioinformatics tools were used to identify membrane proteins. Two hundred and seventeen membrane proteins were detected in the human serum, of which 129 membrane proteins have at least one transmembrane domain (TMD). Further characterizations of identified membrane proteins including their subcellular distributions, molecular weights, post translational modifications, transmembrane domains and average of hydrophobicity, were also implemented. Our results showed the potential of membrane proteins in serum for diagnosis and treatment of diseases.

scholarly journals Immunoglobulin G antibodies directed against protein III block killing of serum-resistant Neisseria gonorrhoeae by immune serum.

1986 ◽  
Vol 164 (5) ◽  
pp. 1735-1748 ◽  
Author(s):  
P A Rice ◽  
H E Vayo ◽  
M R Tam ◽  
M S Blake
Keyword(s):  
Membrane Protein ◽  
Neisseria Gonorrhoeae ◽  
Human Serum ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Immune Serum ◽  
Igg Antibodies ◽  
Porin Protein ◽  
Blocking Activity ◽  
Normal Human

Neisseria gonorrhoeae that resist complement-dependent killing by normal human serum (NHS) are sometimes killed by immune convalescent serum from patients recovering from disseminated gonococcal infection (DGI). In these studies, killing by immune serum was prevented or blocked by IgG isolated from NHS. Purified human IgG antibodies directed against gonococcal protein III, an antigenically conserved outer membrane protein, contained most of the blocking activity in IgG. Antibodies specific for gonococcal porin (protein I), the major outer membrane protein, displayed no blocking function. In separate experiments, immune convalescent DGI serum which did not exhibit bactericidal activity was restored to killing by selective depletion of protein III antibodies by immunoabsorption. These studies indicate that protein III antibodies in normal and immune human serum play a role in serum resistance of N. gonorrhoeae.

scholarly journals Tail-Anchored Inner Membrane Protein ElaB Increases Resistance to Stress While Reducing Persistence in Escherichia coli

2017 ◽  
Vol 199 (9) ◽  
Author(s):  
Yunxue Guo ◽  
Xiaoxiao Liu ◽  
Baiyuan Li ◽  
Jianyun Yao ◽  
Thomas K. Wood ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Stationary Phase ◽  
Transmembrane Domain ◽  
Inner Membrane ◽  
Content Type ◽  
E Coli ◽  
Inner Membrane Protein

ABSTRACT Host-associated bacteria, such as Escherichia coli, often encounter various host-related stresses, such as nutritional deprivation, oxidative stress, and temperature shifts. There is growing interest in searching for small endogenous proteins that mediate stress responses. Here, we characterized the small C-tail-anchored inner membrane protein ElaB in E. coli. ElaB belongs to a class of tail-anchored inner membrane proteins with a C-terminal transmembrane domain but lacking an N-terminal signal sequence for membrane targeting. Proteins from this family have been shown to play vital roles, such as in membrane trafficking and apoptosis, in eukaryotes; however, their role in prokaryotes is largely unexplored. Here, we found that the transcription of elaB is induced in the stationary phase in E. coli and stationary-phase sigma factor RpoS regulates elaB transcription by binding to the promoter of elaB. Moreover, ElaB protects cells against oxidative stress and heat shock stress. However, unlike membrane peptide toxins TisB and GhoT, ElaB does not lead to cell death, and the deletion of elaB greatly increases persister cell formation. Therefore, we demonstrate that disruption of C-tail-anchored inner membrane proteins can reduce stress resistance; it can also lead to deleterious effects, such as increased persistence, in E. coli. IMPORTANCE Escherichia coli synthesizes dozens of poorly understood small membrane proteins containing a predicted transmembrane domain. In this study, we characterized the function of the C-tail-anchored inner membrane protein ElaB in E. coli. ElaB increases resistance to oxidative stress and heat stress, while inactivation of ElaB leads to high persister cell formation. We also demonstrated that the transcription of elaB is under the direct regulation of stationary-phase sigma factor RpoS. Thus, our study reveals that small inner membrane proteins may have important cellular roles during the stress response.

Normal Human Serum Transthyretin Displays Post-Translational Modifications

1996 ◽  
Vol 90 (s34) ◽  
pp. 33P-34P
Author(s):  
W L Hutchinson ◽  
I Longo Alves ◽  
M J Saraiva ◽  
M B Pepys
Keyword(s):  
Human Serum ◽  
Normal Human Serum ◽  
Post Translational Modifications ◽  
Normal Human

On the Complex Formation of Antithrombin III with Thrombin

1973 ◽  
Vol 30 (02) ◽  
pp. 280-283 ◽  
Author(s):  
B Binder
Keyword(s):  
Complex Formation ◽  
Human Serum ◽  
Blood Coagulation ◽  
Antithrombin Iii ◽  
Normal Human Serum ◽  
Molecular Weights ◽  
At Iii ◽  
Normal Human

SummaryBased on gelfiltration studies, the part of AT III which becomes bound to thrombin during the process of in vitro blood coagulation was calculated to be about 40% of total AT III. Complexes consisting of one AT III and one thrombin molecule could not be detected while fractions corresponding to molecular weights of about 190,000 Dalton show AT III as well as thrombin activities. The AT III - thrombin complex in normal human serum consists, therefore, of either 2 AT III and 2 thrombin molecules or of one AT III and 4 thrombin molecules.

scholarly journals A nascent membrane protein is located adjacent to ER membrane proteins throughout its integration and translation.

1991 ◽  
Vol 112 (5) ◽  
pp. 809-821 ◽  
Author(s):  
R N Thrift ◽  
D W Andrews ◽  
P Walter ◽  
A E Johnson
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Transmembrane Domain ◽  
Signal Sequence ◽  
Secretory Protein ◽  
In Vitro Translation ◽  
Nascent Chain ◽  
Transmembrane Sequence ◽  
Er Membrane

The immediate environment of nascent membrane proteins undergoing integration into the ER membrane was investigated by photocrosslinking. Nascent polypeptides of different lengths, each containing a single IgM transmembrane sequence that functions either as a stop-transfer or a signal-anchor sequence, were synthesized by in vitro translation of truncated mRNAs in the presence of N epsilon-(5-azido-2-nitrobenzoyl)-Lys-tRNA, signal recognition particle, and microsomal membranes. This yielded nascent chains with photoreactive probes at one end of the transmembrane sequence where two lysine residues are located. When irradiated, these nascent chains reacted covalently with several ER proteins. One prominent crosslinking target was a glycoprotein similar in size to a protein termed mp39, shown previously to be situated adjacent to a secretory protein during its translocation across the ER membrane (Krieg, U. C., A. E. Johnson, and P. Walter. 1989. J. Cell Biol. 109:2033-2043; Wiedmann, M., D. Goerlich, E. Hartmann, T. V. Kurzchalia, and T. A. Rapoport. 1989. FEBS (Fed. Eur. Biochem. Soc.) Lett. 257:263-268) and likely to be identical to a protein previously designated the signal sequence receptor (Wiedmann, M., T. V. Kurzchalia, E. Hartmann, and T. A. Rapoport. 1987. Nature (Lond.). 328:830-833). Changing the orientation of the transmembrane domain in the bilayer, or making the transmembrane domain the first topogenic sequence in the nascent chain instead of the second, did not significantly alter the identities of the ER proteins that were the primary crosslinking targets. Furthermore, the nascent chains crosslinked to the mp39-like glycoprotein and other microsomal proteins even after the cytoplasmic tail of the nascent chain had been lengthened by nearly 100 amino acids beyond the stop-transfer sequence. Yet when the nascent chain was allowed to terminate normally, the major photocrosslinks were no longer observed, including in particular that to the mp39-like glycoprotein. These results show that the transmembrane segment of a nascent membrane protein is located adjacent to the mp39-like glycoprotein and other ER proteins during the integration process, and that at least a portion of the nascent chain remains in close proximity to these ER proteins until translation has been completed.

scholarly journals Small-residue packing motifs modulate the structure and function of a minimal de novo membrane protein

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Paul Curnow ◽  
Benjamin J. Hardy ◽  
Virginie Dufour ◽  
Christopher J. Arthur ◽  
Richard Stenner ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Transmembrane Domain ◽  
De Novo ◽  
Zinc Protoporphyrin ◽  
Sequence Motifs ◽  
Conserved Sequence ◽  
Starting Point ◽  
Helix Packing ◽  
The Impact

Abstract Alpha-helical integral membrane proteins contain conserved sequence motifs that are known to be important in helix packing. These motifs are a promising starting point for the construction of artificial proteins, but their potential has not yet been fully explored. Here, we study the impact of introducing a common natural helix packing motif to the transmembrane domain of a genetically-encoded and structurally dynamic de novo membrane protein. The resulting construct is an artificial four-helix bundle with lipophilic regions that are defined only by the amino acids L, G, S, A and W. This minimal proto-protein could be recombinantly expressed by diverse prokaryotic and eukaryotic hosts and was found to co-sediment with cellular membranes. The protein could be extracted and purified in surfactant micelles and was monodisperse and stable in vitro, with sufficient structural definition to support the rapid binding of a heme cofactor. The reduction in conformational diversity imposed by this design also enhances the nascent peroxidase activity of the protein-heme complex. Unexpectedly, strains of Escherichia coli expressing this artificial protein specifically accumulated zinc protoporphyrin IX, a rare cofactor that is not used by natural metalloenzymes. Our results demonstrate that simple sequence motifs can rigidify elementary membrane proteins, and that orthogonal artificial membrane proteins can influence the cofactor repertoire of a living cell. These findings have implications for rational protein design and synthetic biology.

scholarly journals Rer1p, a Retrieval Receptor for ER Membrane Proteins, Recognizes Transmembrane Domains in Multiple Modes

2003 ◽  
Vol 14 (9) ◽  
pp. 3605-3616 ◽  
Author(s):  
Ken Sato ◽  
Miyuki Sato ◽  
Akihiko Nakano
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Transmembrane Domain ◽  
Multivesicular Body ◽  
Spatial Location ◽  
Hydrophobic Core ◽  
Polar Residues ◽  
Localization Signal ◽  
Highly Hydrophobic ◽  
Er Membrane

The yeast Golgi membrane protein Rer1p is required for the retrieval of various endoplasmic reticulum (ER) membrane proteins such as Sec12p and Sec71p to the ER. We demonstrate here that the transmembrane domain (TMD) of Sec71p, a type-III membrane protein, contains an ER localization signal, which is required for physical recognition by Rer1p. The Sec71TMD-GFP fusion protein is efficiently retrieved to the ER by Rer1p. The structural feature of this TMD signal turns out to be the spatial location of polar residues flanking the highly hydrophobic core sequence but not the whole length of the TMD. On the Rer1p side, Tyr152 residue in the 4th TMD is important for the recognition of Sec12p but not Sec71p, suggesting that Rer1p interacts with its ligands at least in two modes. Sec71TMD-GFP expressed in the Δrer1 mutant cells is mislocalized from the ER to the lumen of vacuoles via the multivesicular body (MVB) sorting pathway. In this case, not only the presence of polar residues in the Sec71TMD but also the length of the TMD is critical for the MVB sorting. Thus, the Rer1p-dependent ER retrieval and the MVB sorting in late endosomes both watch polar residues in the TMD but in a different manner.

A transmembrane serine residue in the Rot1 protein is essential for yeast cell viability

2014 ◽  
Vol 458 (2) ◽  
pp. 239-249 ◽  
Author(s):  
Carlos A. Martínez-Garay ◽  
M. Angeles Juanes ◽  
J. Carlos Igual ◽  
Ismael Mingarro ◽  
M. Carmen Bañó
Keyword(s):  
Amino Acids ◽  
Cell Death ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Cell Viability ◽  
Yeast Cell ◽  
Protein Function ◽  
Transmembrane Domain ◽  
Transmembrane Helices ◽  
Serine Residue

Polar residues present in transmembrane helices influence the folding or association of membrane proteins. Rot1 is a membrane protein with a single transmembrane domain. Replacement of a serine residue in the transmembrane domain by different amino acids precluded protein function, causing cell death.

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