Abstract:
:A fraction obtained by gel filtration at neutral pH of the extracellular Hb of Lumbricus terrestris dissociated either at pH 9.8 or at pH 4.0, consisting of the three subunits D1 (31 kDa), D2 (37 kDa), and T (50 kDa), was found to produce two peaks when subjected to gel filtration on Superose 6 at pH 7. The first peak, which was eluted at a slightly greater volume than the native Hb, consisted of reassociated hexagonal bilayer structures when examined by scanning transmission electron microscopy. The dimensions of the two reassociated hexagonal bilayer structures were a vertex-to-vertex diameter of 25 nm and a height of 16 nm. The difference in size between the hexagonal bilayer structures and the native Hb is the contribution of subunit M, which consists of a single heme-containing chain I (16.75 kDa). Although the reassociated hexagonal bilayer structures have overall dimensions smaller than the 30 nm x 20 nm dimensions of the native Hb, the diameters of the central cavities are not substantially altered. Subtraction of the three-dimensional reconstructions of the reassociated hexagonal bilayer structures from those of the native Hb showed that subunit M was primarily localized at the periphery of Lumbricus Hb. The formation of hexagonal bilayer structures in the complete absence of subunit M provides additional support for the "bracelet" model of the quaternary structure of Lumbricus Hb proposed recently by us in which subunits D1 and D2 were assumed to act as linkers for complexes of subunits M and T or to form a "bracelet" decorated with 12 complexes of subunits M and T.
journal_name
Proc Natl Acad Sci U S Aauthors
Kapp OH,Mainwaring MG,Vinogradov SN,Crewe AVdoi
10.1073/pnas.84.21.7532subject
Has Abstractpub_date
1987-11-01 00:00:00pages
7532-6issue
21eissn
0027-8424issn
1091-6490journal_volume
84pub_type
杂志文章abstract::West Nile virus, which is transmitted by Culex mosquitoes while feeding on birds and humans, has emerged as the dominant vector borne disease in North America. We have identified natural compounds from humans and birds, which are detected with extreme sensitivity by olfactory receptor neurons (ORNs) on the antennae 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.0906932106
更新日期:2009-11-03 00:00:00
abstract::Von Willebrand factor-binding protein (VWbp), secreted by Staphylococcus aureus, displays secondary structural homology to the 3-helix bundle, D1 and D2 domains of staphylocoagulase (SC), a potent conformational activator of the blood coagulation zymogen, prothrombin (ProT). In contrast to the classical proteolytic ac...
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.0811750106
更新日期:2009-05-12 00:00:00
abstract::Posttranscriptional RNA regulation is important in determining the plasticity of cellular phenotypes. However, mechanisms of how RNA binding proteins (RBPs) influence cellular behavior are poorly understood. We show here that the RBP embryonic lethal abnormal vision like 1 (ELAVL1, also know as HuR) regulates the alte...
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.1412172111
更新日期:2014-12-23 00:00:00
abstract::A protein of 87 kilodaltons (87 kDa) was previously identified as a major specific substrate for protein kinase C in neuronal and other tissues. We have now studied the effect of protein kinase C-catalyzed phosphorylation of this protein on its association with membranes in isolated nerve terminals (synaptosomes) from...
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.86.7.2253
更新日期:1989-04-01 00:00:00
abstract::We report the nucleotide sequences of iaaM and iaaH, the genetic determinants for, respectively, tryptophan 2-monooxygenase and indoleacetamide hydrolase, the enzymes that catalyze the conversion of L-tryptophan to indoleacetic acid in the tumor-forming bacterium Pseudomonas syringae pv. savastanoi. The sequence analy...
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.82.19.6522
更新日期:1985-10-01 00:00:00
abstract::We recently reported that CD3- natural killer (NK) cells express the zeta chain of the T-cell receptor complex (zeta NK) in association with higher molecular weight structures whose expression differs between individual NK cell clones. Because NK cell cytolytic activity is known to be triggered by perturbation of the ...
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.87.6.2274
更新日期:1990-03-01 00:00:00
abstract::Accumulating evidence suggests cancer cells exhibit a dependency on metabolic pathways regulated by nicotinamide adenine dinucleotide (NAD+). Nevertheless, how the regulation of this metabolic cofactor interfaces with signal transduction networks remains poorly understood in glioblastoma. Here, we report nicotinamide ...
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.1610921114
更新日期:2016-12-20 00:00:00
abstract::Lithium is the most commonly used drug for the treatment of manic depressive illness. The precise mechanisms underlying its clinical efficacy remain unknown. We found that long-term exposure to lithium chloride dramatically protects cultured rat cerebellar, cerebral cortical, and hippocampal neurons against glutamate-...
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.95.5.2642
更新日期:1998-03-03 00:00:00
abstract::Monkeypox virus (MPV) is a virulent human pathogen that has gained increased attention because of its potential use as a bioterrorism agent and inadvertent introduction into North America in 2003. The US outbreak also provided an important opportunity to study MPV-specific T cell immunity. Although MPV-specific CD4(+)...
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.0800589105
更新日期:2008-09-23 00:00:00
abstract::This report describes the integration of laser-scanning fluorometric cytometry and nonseparation ligand-binding techniques to provide new assay methods adaptable to miniaturization and high-throughput screening. Receptor-bound, cyanine dye-labeled ligands, [Cy]ligands, were discriminated from those free in solution by...
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.96.20.11122
更新日期:1999-09-28 00:00:00
abstract::Spectrin is an important structural component of the plasma membrane skeleton. Heretofore-unidentified isoforms of spectrin also associate with Golgi and other organelles. We have discovered another member of the beta-spectrin gene family by homology searches of the GenBank databases and by 5' rapid amplification of c...
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.95.24.14158
更新日期:1998-11-24 00:00:00
abstract::Cyclotides are plant defense peptides that have been extensively investigated for pharmaceutical and agricultural applications, but key details of their posttranslational biosynthesis have remained elusive. Asparaginyl endopeptidases are crucial in the final stage of the head-to-tail cyclization reaction, but the enzy...
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.1901807116
更新日期:2019-04-16 00:00:00
abstract::A comparison of five constant region sequences of human and mouse k and lambda immunoglobulin chains has been undertaken in order to reveal sequence homologies and evolutionary relationships. Simultaneously, a comparison with the three-dimensional structure of one mouse k-chain (McPC 603) has suggested structural reas...
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.72.7.2785
更新日期:1975-07-01 00:00:00
abstract::Phosphatidylcholine (PC) is the major glycerophospholipid in eukaryotic cells and is an essential component in all cellular membranes. The biochemistry of de novo PC synthesis by the Kennedy pathway is well established, but less is known about the physiological functions of PC. We identified two unrelated patients wit...
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.1408523111
更新日期:2014-06-17 00:00:00
abstract::The fundamental questions of how lubricant molecules organize into a layered structure under nanometers confinement and what is the interplay between layering and friction are still not well answered in the field of nanotribology. While the phase transition of lubricants during a squeeze-out process under compression ...
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.1805569115
更新日期:2018-06-26 00:00:00
abstract::Ribbon synapses of photoreceptor cells and second-order bipolar neurons in the retina are specialized to transmit graded signals that encode light intensity. Neurotransmitter release at ribbon synapses exhibits two kinetically distinct components, which serve different sensory functions. The faster component is deplet...
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.1323962111
更新日期:2014-06-10 00:00:00
abstract::A mechanistic understanding of the controls on carbon storage and losses is essential for our capacity to predict and mitigate human impacts on the global carbon cycle. Plant litter decomposition is an important first step for carbon and nutrient turnover, and litter inputs and losses are essential in determining soil...
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.1516157113
更新日期:2016-04-19 00:00:00
abstract::Expression of glucokinase in hepatocytes and pancreatic 6-cells is of major physiologic importance to mammalian glucose homeostasis. Liver glucokinase catalyzes the first committed step in the disposal of glucose, and beta-cell glucokinase catalyzes a rate-limiting step required for glucose-regulated insulin release. ...
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.93.14.7036
更新日期:1996-07-09 00:00:00
abstract::Plasmons, the collective oscillations of interacting electrons, possess emergent properties that dramatically alter the optical response of metals. We predict the existence of a new class of plasmons-chiral Berry plasmons (CBPs)-for a wide range of 2D metallic systems including gapped Dirac materials. As we show, in t...
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.1519086113
更新日期:2016-04-26 00:00:00
abstract::Filipin, digitonin, and saponin react with membrane cholesterol to produce unique membrane alterations (sterol-specific complexes) that are easily discernible in freeze-fracture replicas. We have treated both noninnervated and innervated Xenopus embryonic muscle cells in culture with these agents. Freeze-fracture of t...
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.78.2.1278
更新日期:1981-02-01 00:00:00
abstract::Ca(2+) is known to have important roles in sperm chemotaxis, although the relationship between intracellular Ca(2+) concentration ([Ca(2+)](i)) and modulation of the swimming and chemotactic behavior of spermatozoa has not been elucidated. Using a high-speed Ca(2+) imaging system, we examined the chemotactic behavior ...
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.0808580105
更新日期:2008-12-09 00:00:00
abstract::Particle tracking is a powerful biophysical tool that requires conversion of large video files into position time series, i.e., traces of the species of interest for data analysis. Current tracking methods, based on a limited set of input parameters to identify bright objects, are ill-equipped to handle the spectrum o...
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.1804420115
更新日期:2018-09-04 00:00:00
abstract::CPEB, a cytoplasmic polyadenylation element-binding protein, plays an important role in translational control of maternal mRNAs in early animal development. During Xenopus oocyte maturation, CPEB undergoes a Cdc2-mediated phosphorylation- and ubiquitin-dependent degradation that is required for proper entry into meios...
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.0706952104
更新日期:2007-11-13 00:00:00
abstract::The severe acute respiratory syndrome coronavirus 2 originated in Wuhan, China at the end of 2019 and rapidly spread in more than 100 countries. Researchers in different fields have been working on finding explanations for the unequal impact of the virus and deaths from the associated coronavirus disease 2019 (COVID-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.2008581117
更新日期:2020-08-11 00:00:00
abstract::Maternal infections during pregnancy are associated with increased risk of neurodevelopmental disorders, although the precise mechanisms remain to be elucidated. Previously, we established a maternal immune activation (MIA) model using swine, which results in altered social behaviors of piglet offspring. These behavio...
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.1817014116
更新日期:2019-10-01 00:00:00
abstract::To examine the in vivo role(s) of type I interferons (IFNs) and to determine the role of a component of the type I IFN receptor (IFNAR1) in mediating responses to these IFNs, we generated mice with a null mutation (-/-) in the IFNAR1 gene. Despite compelling evidence for modulation of cell proliferation and differenti...
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.92.24.11284
更新日期:1995-11-21 00:00:00
abstract::A strong mutator effect has been observed in Escherichia coli K-12 strains mutated in the bglY gene (27 min). The frequency of point mutations is not modified in bglY mutant strains. In contrast, a strong increase in spontaneous generation of large deletions has been observed in these strains, both for chromosomal mar...
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.87.1.360
更新日期:1990-01-01 00:00:00
abstract::Recent theory suggests that animals should switch facultatively among canonical movement modes as a complex function of internal state, landscape characteristics, motion capacity, and navigational capacity. We tested the generality of this paradigm for free-ranging elk (Cervus elaphus) over 5 orders of magnitude in ti...
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.0801737105
更新日期:2008-12-09 00:00:00
abstract::Recent findings suggest that neurons can efficiently repair oxidatively damaged DNA, and that both DNA damage and repair are enhanced by activation of excitatory glutamate receptors. However, in pathological conditions such as ischemic stroke, excessive DNA damage can trigger the death of neurons. Oxidative DNA damage...
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.1204156109
更新日期:2012-09-11 00:00:00
abstract::Gene regulatory networks (GRNs) provide a transformation function between the static genomic sequence and the primary spatial specification processes operating development. The regulatory information encompassed in developmental GRNs thus goes far beyond the control of individual genes. We here address regulatory info...
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.1610616114
更新日期:2017-06-06 00:00:00