Abstract:
:In earlier studies with the acetylcholine receptor (AcChoR) of Electrophorus electricus the rate and equilibrium constants for a model that relates the ligand binding to ion translocation were determined, and the dependence of these constants on the concentrations of carbamoylcholine and acetylcholine, over a 200- and 5000-fold range, respectively, could be predicted. AcChoR-controlled cation flux has now been measured in Torpedo californica vesicles by using a pulsed-quench-flow technique with a 2-msec time resolution. Torpedo vesicles on a weight basis may contain several hundred times more receptor sites than do E. electricus vesicles. Techniques have been developed to (i) correct for the kinetic heterogeneity of the vesicle population; (ii) use the inactivation of the receptor by its natural ligand to reduce influx rates at high ligand concentrations to a measurable level (this permitted J(A), the influx rate coefficient before the onset of inactivation, to be measured); and (iii) determine the rate coefficients of two processes that lead to successive inactivations (desensitization) of the receptor and occur in different time regions. An extension of a model proposed for the E. electricus receptor accommodates the ion translocation in T. californica vesicles. The features in common are: (i) A rapid initial flux rate [J(A)(max) for T. californica is 310 sec(-1); for E. electricus it is 7.5 sec(-1)]. These differences in flux rates are consistent with a difference in AcChoR density. (ii) A rapid inactivation process [alpha(max) for T. californica is 2 sec(-1); for E. electricus it is 7 sec(-1)]. (iii) A slow AcChoR-controlled flux that continues after the rapid inactivation [J(I)(max) for T. californica is 1.3 sec(-1); for E. electricus it is 0.015 sec(-1)]. The main difference between the flux in the two types of vesicle is the existence of a second, slower, inactivation process in T. californica with a rate coefficient, beta, of 0.12 sec(-1). The second process leads to undetectable flux activity during the time of observation (30 sec in 10 mM carbamoylcholine). These studies are also significant because fundamental differences may exist between the mechanism of AcChoR-controlled ion flux in synaptic (Torpedo) and conducting (E. electricus) membranes.
journal_name
Proc Natl Acad Sci U S Aauthors
Hess GP,Pasquale EB,Walker JW,McNamee MGdoi
10.1073/pnas.79.4.963subject
Has Abstractpub_date
1982-02-01 00:00:00pages
963-7issue
4eissn
0027-8424issn
1091-6490journal_volume
79pub_type
杂志文章abstract::The combination of catalytic amounts of optically active dipyridylphosphine and CuF(2) along with hydride donor PhSiH(3) generated in situ a remarkably reactive catalyst system (substrate-to-ligand molar ratio up to 100,000) for the highly enantioselective hydrosilylation of a broad spectrum of aryl alkyl ketones (up ...
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.0409043102
更新日期:2005-03-08 00:00:00
abstract::Several cDNA clones encoding the human immunoglobulin G receptor CD16 were isolated from human lung or peripheral blood leukocyte cDNA libraries. Nucleotide sequence comparisons revealed that the cDNAs could be divided into two groups. cDNA clones in one group encode a protein that terminates 4 amino acids after the p...
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.86.13.5079
更新日期:1989-07-01 00:00:00
abstract::Overlapping cDNAs derived from the chicken alpha-fibrinogen mRNA have been sequenced, beginning from within the coding region for the signal peptide of this subunit and terminating within the poly(A) extension. The predicted size of chicken alpha-fibrinogen is 54,187 daltons, which is the smallest of any alpha chain r...
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.87.13.5198
更新日期:1990-07-01 00:00:00
abstract::One of the morphological hallmarks of terminally differentiated secretory cells is highly proliferated membrane of the rough endoplasmic reticulum (ER), but the molecular basis for the high rate of protein biosynthesis in these cells remains poorly documented. An important aspect of ER translational control is the mol...
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.1901742116
更新日期:2019-05-07 00:00:00
abstract::N-methyl-d-aspartate receptors (NMDARs) mediate critical CNS functions, whereas excessive activity contributes to neuronal damage. At physiological glycine concentrations, NMDAR currents recorded from cultured rodent hippocampal neurons exhibited strong desensitization in the continued presence of NMDA, thus protectin...
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.1110789109
更新日期:2012-01-31 00:00:00
abstract::The epothilones represent a promising class of natural product-based antitumor drug candidates. Although these compounds operate through a microtubule stabilization mechanism similar to that of taxol, the epothilones offer a major potential therapeutic advantage in that they retain their activity against multidrug-res...
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.0804773105
更新日期:2008-09-02 00:00:00
abstract::Streptococcus pneumoniae is a major human pathogen that successfully adapts to the host environment via an efficient uptake system for free DNA liberated from other organisms in the upper respiratory tract, facilitating immune evasion and drug resistance. Although the initial signaling events leading to pneumococcal 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.1313860111
更新日期:2014-02-18 00:00:00
abstract::Lactobacillus acidophilus NCFM is a probiotic bacterium that has been produced commercially since 1972. The complete genome is 1,993,564 nt and devoid of plasmids. The average GC content is 34.71% with 1,864 predicted ORFs, of which 72.5% were functionally classified. Nine phage-related integrases were predicted, but ...
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.0409188102
更新日期:2005-03-15 00:00:00
abstract::Functional MRI based on blood oxygenation level-dependent (BOLD) contrast is well established as a neuroimaging technique for detecting neural activity in the cortex of the human brain. While detection and characterization of BOLD signals, as well as their electrophysiological and hemodynamic/metabolic origins, have 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.1711567115
更新日期:2018-01-16 00:00:00
abstract::The paucity of knowledge about cardiomyocyte maturation is a major bottleneck in cardiac regenerative medicine. In development, cardiomyocyte maturation is characterized by orchestrated structural, transcriptional, and functional specializations that occur mainly at the perinatal stage. Sarcomeres are the key cytoskel...
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.2008861118
更新日期:2021-01-12 00:00:00
abstract::Drug-target residence time (t = 1/k(off), where k(off) is the dissociation rate constant) has become an important index in discovering better- or best-in-class drugs. However, little effort has been dedicated to developing computational methods that can accurately predict this kinetic parameter or related parameters, ...
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.1301814110
更新日期:2013-03-12 00:00:00
abstract::The fluorescent probes acridine orange and oxonol-V were used as indicators of pH gradients (DeltapH) and membrane potential differences (DeltaPsi), respectively, in membrane vesicles believed to be derived from the tonoplast of Beta vulgaris L. Low concentrations of nitrate (1-5 mM) caused a partial dissipation of bo...
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.82.11.3683
更新日期:1985-06-01 00:00:00
abstract::Classical eyeblink conditioning is a well-characterized model paradigm that engages the septohippocampal cholinergic system. This form of associative learning is impaired in normal aging and severely disrupted in Alzheimer's disease (AD). Some nicotinic cholinergic receptor subtypes are lost in AD, making the use of n...
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.031584398
更新日期:2001-02-13 00:00:00
abstract::Human malignant pleural mesothelioma (MPM) is considered a rare tumor, but recent estimations indicate that one-quarter million people will die of this neoplasm in Europe in the next three decades. The mineral asbestos is considered the main causative agent of this neoplasm. MPM is largely unresponsive to conventional...
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.1213238109
更新日期:2012-10-30 00:00:00
abstract::The memory for a new episode is formed immediately upon experience and can last up to a lifetime. It has been shown that the hippocampal network plays a fundamental role in the rapid acquisition of a memory of a one-time experience, in which the novelty component of the experience promotes the prompt formation 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.1714082115
更新日期:2018-01-09 00:00:00
abstract::Although nanoparticle-protein conjugates have been synthesized for numerous applications, bioconjugation remains a challenge, often resulting in denaturation or loss of protein function. This is partly because the protein-nanoparticle interface is poorly understood, which impedes the use of nanoparticles in nanomedici...
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.0807299106
更新日期:2009-03-17 00:00:00
abstract::Developmental constraint is indicated when one finds that similar genetic mechanisms are responsible for independent origins of the same derived phenotype. We studied three independent origins of rosette flowering within the mustard family and attempted to evaluate the extent to which the same mechanisms were involved...
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.0401824101
更新日期:2004-04-27 00:00:00
abstract::AAV is unique among eukaryotic viruses in the ability of its DNA to integrate preferentially into a specific region of the human genome. Understanding AAV integration may aid in developing gene therapy systems with predictable integration sites. Using a gel mobility-shift assay, we have identified a DNA sequence withi...
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.91.13.5808
更新日期:1994-06-21 00:00:00
abstract::It has been shown previously that the binding of oxidized low-density lipoprotein (OxLDL) to resident mouse peritoneal macrophages can be inhibited (up to 70%) by the apoprotein B (apoB) isolated from OxLDL, suggesting that macrophage recognition of OxLDL is primarily dependent on its modified protein moiety. However,...
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.96.11.6347
更新日期:1999-05-25 00:00:00
abstract::The only major glutamate receptor membrane-associated guanylate kinase scaffolds expressed in the young superficial superior colliculus (SC) are synapse-associated protein 102 (SAP102) and postsynaptic density protein 95 (PSD95). In this, as in all visual brain regions examined, synaptic PSD95 increases rapidly follow...
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.1215854110
更新日期:2013-01-08 00:00:00
abstract::Members of the polo subfamily of protein kinases play pivotal roles in cell-cycle control and proliferation. In addition to a high degree of sequence similarity in the kinase domain, polo kinases contain a strikingly conserved motif termed "polo-box" in the noncatalytic C-terminal domain. We have previously shown that...
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.96.25.14360
更新日期:1999-12-07 00:00:00
abstract::Asymmetric cell division (ACD) is believed to be a physiological event that occurs during development and tissue homeostasis in a large variety of organisms. ACD produces two unequal daughter cells, one of which resembles a multipotent stem and/or progenitor cell, whereas the other has potential for differentiation. A...
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.1205525109
更新日期:2012-10-30 00:00:00
abstract::The x-ray crystal structures of the sulfide oxidase antibody 28B4 and of antibody 28B4 complexed with hapten have been solved at 2.2-angstrom and 1.9-angstrom resolution, respectively. To our knowledge, these structures are the highest resolution catalytic antibody structures to date and provide insight into the molec...
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.93.11.5363
更新日期:1996-05-28 00:00:00
abstract::Experiments were performed to ascertain the degree to which the amount of amino acids might be one of the regulatory factors that control the activity of the nucleolar RNA polymerase. Assays of the enzymatic activity were done with isolated nuclei from cells incubated with low and high concentrations of amino acids. S...
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.68.12.3040
更新日期:1971-12-01 00:00:00
abstract::Cells of the human embryonic stem (hES) cell line H9, when cultured in the form of embryoid bodies, give rise to cells with markers of the keratinocyte of stratified squamous epithelia. Keratinocytes also form in nodules produced in scid mice by injected H9 cells; the hES-derived keratinocytes could be recovered in cu...
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.0510953103
更新日期:2006-02-07 00:00:00
abstract::Growth of 3T3-L2 fibroblasts in medium containing 5-bromo-2'-deoxyuridine prevents the spontaneous cytodifferentiation of these cells into adipose cells. Treatment of bromodeoxyuridine-suppressed cultures at confluence with 1-methyl-3-isobutylxanthine, a promoter of the adipose conversion, results in differentiation 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.76.9.4451
更新日期:1979-09-01 00:00:00
abstract::Release of formylmethionine from the reticulocyte ribosomal substrate, f[(3)H]Met-tRNA.ribosome, is promoted by reticulocyte release factor (RF). The initial rate of this reaction is stimulated by GTP but inhibited by GDPCP. Formation of an RF.UA[(3)H]A(2).ribosome complex is a measure of the binding of reticulocyte R...
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.70.8.2350
更新日期:1973-08-01 00:00:00
abstract::The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibr...
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.97.21.11614
更新日期:2000-10-10 00:00:00
abstract::Bacillus anthracis, the etiologic agent of anthrax, avoids immune surveillance and commandeers host macrophages as a vehicle for lymphatic spreading. Here, we show that B. anthracis edema toxin (ET), via its adenylyl cyclase activity, dramatically increases the motility of infected macrophages and the expression of va...
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.0800105105
更新日期:2008-04-22 00:00:00
abstract::Myosin V, a double-headed molecular motor, transports organelles within cells by walking processively along actin, a process that requires coordination between the heads. To understand the mechanism underlying this coordination, processive runs of single myosin V molecules were perturbed by varying nucleotide content....
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.0307247101
更新日期:2004-04-13 00:00:00