Abstract:
:The Escherichia coli cytosolic homotetrameric protein SecB is known to be involved in protein export across the plasma membrane. A currently prevalent view holds that SecB functions exclusively as a chaperone interacting nonspecifically with unfolded proteins, not necessarily exported proteins, whereas a contrary view holds that SecB functions primarily as a specific signal-recognition factor--i.e., in binding to the signal sequence region of exported proteins. To experimentally resolve these differences we assayed for binding between chemically pure SecB and chemically pure precursor (p) form (containing a signal sequence) and mature (m) form (lacking a signal sequence) of a model secretory protein (maltose binding protein, MBP) that was C-terminally truncated. Because of the C-terminal truncation, neither p nor m was able to fold. We found that SecB bound with 100-fold higher affinity to p (Kd 0.8 nM) than it bound to m (Kd 80 nM). As the presence of the signal sequence in p is the only feature that distinguished p from m, these data strongly suggest that the high-affinity binding of SecB is to the signal sequence region and not the mature region of p. Consistent with this conclusion, we found that a wild-type signal peptide, but not an export-incompetent mutant signal peptide of another exported protein (LamB), competed for binding to p. Moreover, the high-affinity binding of SecB to p was resistant to 1 M salt, whereas the low-affinity binding of SecB to m was not. These qualitative differences suggested that SecB binding to m was primarily by electrostatic interactions, whereas SecB binding to p was primarily via hydrophobic interactions, presumably with the hydrophobic core of the signal sequence. Taken together our data strongly support the notion that SecB is primarily a specific signal-recognition factor.
journal_name
Proc Natl Acad Sci U S Aauthors
Watanabe M,Blobel Gdoi
10.1073/pnas.92.22.10133subject
Has Abstractpub_date
1995-10-24 00:00:00pages
10133-6issue
22eissn
0027-8424issn
1091-6490journal_volume
92pub_type
杂志文章abstract::Lipopolysaccharide (LPS) is the major glycolipid that is present in the outer membranes (OMs) of most Gram-negative bacteria. LPS molecules are assembled with divalent metal cations in the outer leaflet of the OM to form an impervious layer that prevents toxic compounds from entering the cell. For most Gram-negative b...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0912872107
更新日期:2010-03-23 00:00:00
abstract::We investigated the binding of 125I-labeled alpha-inhibin-92 (a 92-residue peptide) to human pituitary membrane preparations. Unlabeled alpha-inhibin-92 competed effectively with the labeled peptide for binding to the membranes. Binding was also inhibited by both alpha-inhibin-52 and alpha-inhibin-31, but less effecti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.11.3595
更新日期:1987-06-01 00:00:00
abstract::Electrochemistry is an old but still flourishing field of research due to the importance of the efficiency and kinetics of electrochemical reactions in industrial processes and (bio-)electrochemical devices. The heterogeneous electron transfer from an electrode to a reactant in the solution has been well studied for m...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1806087115
更新日期:2018-11-20 00:00:00
abstract::Antisense oligodeoxyribonucleotides targeted to the epidermal growth factor (EGF) receptor were encapsulated into liposomes linked to folate via a polyethylene glycol spacer (folate-PEG-liposomes) and efficiently delivered into cultured KB cells via folate receptor-mediated endocytosis. The oligonucleotides were a pho...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.8.3318
更新日期:1995-04-11 00:00:00
abstract::Genetic switches based on the [Formula: see text] system are master regulators of an array of cellular responses. Recent kinetic experiments have shown that [Formula: see text] can actively remove NF-κB bound to its genetic sites via a process called "molecular stripping." This allows the [Formula: see text] switch to...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1520483112
更新日期:2016-01-05 00:00:00
abstract::d-alanine-d-lactate ligase from Enterococcus faecium BM4147 is directly responsible for the biosynthesis of alternate cell-wall precursors in bacteria, which are resistant to the glycopeptide antibiotic vancomycin. The crystal structure has been determined with data extending to 2.5-A resolution. This structure shows ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.150116497
更新日期:2000-08-01 00:00:00
abstract::Embryogenesis requires the precise activation and repression of many transcriptional regulators. The Polycomb group proteins and the associated H3K27me3 histone mark are essential to maintain the inactive state of many of these genes. Mammalian Hox genes are targets of Polycomb proteins and form local 3D clusters cent...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1504783112
更新日期:2015-04-14 00:00:00
abstract::The G protein-coupled free fatty acid receptor-1 (FFA1/GPR40) plays a major role in the regulation of insulin secretion by fatty acids. GPR40 is considered a potential therapeutic target to enhance insulin secretion in type 2 diabetes; however, its mode of regulation is essentially unknown. The aims of this study were...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1114350109
更新日期:2012-02-14 00:00:00
abstract::Although the Austronesian expansion had a major impact on the languages of Island Southeast Asia, controversy still exists over the genetic impact of this expansion. The coexistence of both Asian and Papuan genetic ancestry in Eastern Indonesia provides a unique opportunity to address this issue. Here, we estimate rec...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1118892109
更新日期:2012-03-20 00:00:00
abstract::A 1H NMR study of the 79-residue globular domain of chicken erythrocyte histone H5 (GH5) is presented. Using a combination of two-dimensional NMR techniques to demonstrate through-bond and through-space (less than 5 A) connectivities, the resonances of GH5 are assigned in a sequential manner. From a qualitative interp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.20.7628
更新日期:1986-10-01 00:00:00
abstract::The ATP-binding cassette (ABC) transporter of mitochondria (Atm1) mediates iron homeostasis in eukaryotes, while the prokaryotic homolog from Novosphingobium aromaticivorans (NaAtm1) can export glutathione derivatives and confer protection against heavy-metal toxicity. To establish the structural framework underlying ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2006526117
更新日期:2020-08-11 00:00:00
abstract::The covalent linkage of supramolecular monomers provides a powerful strategy for constructing dynamic polymeric materials whose properties can be readily tuned either by the selection of monomers or the choice of functional linkers. In this strategy, the stabilities of the supramolecular monomers and the reactions use...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1612898113
更新日期:2016-10-04 00:00:00
abstract::Enteritis caused by Clostridium difficile toxin (Tx) is a nosocomial disease of increasing clinical concern, but the local mediators of C. difficile TxA inflammation are unknown. The potent vasodilator calcitonin gene-related peptide mediates neurogenic inflammation via the calcitonin receptor-like receptor (CLR). Her...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1219733110
更新日期:2013-01-08 00:00:00
abstract::Aqueous gel sieving chromatography on Sephadex G-10 of the Group IA cations (Li+, Na+, K+, Rb+, Cs+) plus NH4+ as the Cl- salts, in combination with previous results for the halide anions (F-, Cl-, Br-, I-) as the Na+ salts [Washabaugh, M.W. & Collins, K.D. (1986) J. Biol. Chem. 261, 12477-12485], leads to the followi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.12.5553
更新日期:1995-06-06 00:00:00
abstract::A genetic defect in a CC-chemokine receptor (CCR)-5, the principal coreceptor for the macrophage-tropic HIV type 1 (HIV-1), recently was found to naturally protect CCR-5-defective, but healthy, individuals from HIV-1 infection. In this study, we mimic the natural resistance of the CCR-5-defective individuals by design...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.21.11567
更新日期:1997-10-14 00:00:00
abstract::The intracellular pathogen Salmonella enterica serovar Typhimurium requires the mgtC gene to cause disease. The mgtC transcript includes a long leader region that harbors a short proline codon-rich ORF--termed mgtP--the translation of which is predicted to favor formation of one of two alternative stem-loop structures...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1316209111
更新日期:2014-02-25 00:00:00
abstract::Maternal microchimerism (MMc) has been associated with development of allospecific transplant tolerance, antitumor immunity, and cross-generational reproductive fitness, but its mode of action is unknown. We found in a murine model that MMc caused exposure to the noninherited maternal antigens in all offspring, but in...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1618364114
更新日期:2017-01-31 00:00:00
abstract::We used a sensitive and specific cDNA polymerase chain reaction assay to detect hepatitis C virus (HCV) RNA in serum samples from 128 unselected southern African Blacks with hepatocellular carcinoma (HCC) and found HCV RNA in 26 (20.3%) of these patients. Antibodies to HCV (anti-HCV) were detected in 59 patients (46.1...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.5.1848
更新日期:1993-03-01 00:00:00
abstract::L-Asparaginase (EC 3.5.1.1) inhibited respiration in sensitive, but not resistant, lines of murine lymphoma 6C3HED. Glucose, in these tumor lines, was principally converted to lactate, and very little was oxidized in the citric acid cycle or hexose monophosphate shunt. The cells derived 70-80% of their respiratory CO(...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.71.10.3993
更新日期:1974-10-01 00:00:00
abstract::Development of type 1 diabetes in the nonobese diabetic (NOD) mouse is preceded by an immune cell infiltrate in the pancreatic islets. The exact role of the attracted cells is still poorly understood. Chemokine CCL2/MCP-1 is known to attract CCR2(+) monocytes and dendritic cells (DCs). We have previously shown that tr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1115308109
更新日期:2012-02-28 00:00:00
abstract::The amino acid sequence of the light chain of bovine protein C was determined by sequenator analysis of the carboxymethylated light chain and fragments obtained by cyanogen bromide treatment, tryptic digestion after blocking of lysine residues, and cleavage with 2-(2-nitrophenylsulfenyl)-3-methyl-3-bromoindolenine (BN...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.75.12.5889
更新日期:1978-12-01 00:00:00
abstract::Glycosylation is one of the most common posttranslational modifications to occur in protein biosynthesis, yet its effect on the thermodynamics and kinetics of proteins is poorly understood. A minimalist model based on the native protein topology, in which each amino acid and sugar ring was represented by a single bead...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0801340105
更新日期:2008-06-17 00:00:00
abstract::A 6.2-kb full-length clone encoding a distinct protein-tyrosine phosphatase (PTP; EC 3.1.3.48), PTPD1, was isolated from a human skeletal muscle cDNA library. The cDNA encodes a protein of 1174 amino acids with N-terminal sequence homology to the ezrin-band 4.1-merlin-radixin protein family, which also includes the tw...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.16.7477
更新日期:1994-08-02 00:00:00
abstract::Small RNAs (sRNAs) are important components of posttranscriptional regulation. These molecules are prevalent in bacterial and eukaryotic organisms, and involved in a variety of responses to environmental stresses. The functional characterization of sRNAs is challenging and requires highly focused and extensive experim...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1104318108
更新日期:2011-09-13 00:00:00
abstract::Tyrosine kinases of the Janus kinase family initiate cellular responses through their association with receptors for alpha-helical cytokines. In addition to a tyrosine kinase domain, these enzymes possess a kinase-like (KL) domain, whose function remains elusive. To investigate the role of the KL domain of Tyk2 in int...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.160130297
更新日期:2000-08-01 00:00:00
abstract::Niemann-Pick C1 (NPC1) and NPC2 proteins are indispensable for the export of LDL-derived cholesterol from late endosomes. Mutations in these proteins result in Niemann-Pick type C disease, a lysosomal storage disease. Despite recent reports of the NPC1 structure depicting its overall architecture, the function of its ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1711716114
更新日期:2017-08-22 00:00:00
abstract::Cytochrome ba3 from Thermus thermophilus reacts slowly with excess HCN at pH 7.4 to create a form of the enzyme in which CuA, cytochrome b, and CuB remain oxidized, while cytochrome a3 is reduced by one electron, presumably with the formation of cyanogen. We have examined this form of the enzyme by UV-visible, resonan...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.8.3195
更新日期:1992-04-15 00:00:00
abstract::During the analysis of liver protein expression in the offspring of male mice irradiated with fission-spectrum neutrons, one offspring displayed a heritable 50% decrease in the abundance of two proteins. Homozygous mice lacking detectable quantities of these proteins were obtained through breeding. Characterization of...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.24.11338
更新日期:1994-11-22 00:00:00
abstract::Humans choose actions based on both habit and planning. Habitual control is computationally frugal but adapts slowly to novel circumstances, whereas planning is computationally expensive but can adapt swiftly. Current research emphasizes the competition between habits and plans for behavioral control, yet many complex...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1506367112
更新日期:2015-11-10 00:00:00
abstract::Renal excretion of water and major electrolytes exhibits a significant circadian rhythm. This functional periodicity is believed to result, at least in part, from circadian changes in secretion/reabsorption capacities of the distal nephron and collecting ducts. Here, we studied the molecular mechanisms underlying circ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0904890106
更新日期:2009-09-22 00:00:00