Abstract:
:The effect of intracellular (i) and extracellular (o) Na+ on pre-steady-state transient current associated with Na+/Na+ exchange by the Na+/K+ pump was investigated in the vegetal pole of Xenopus oocytes. Current records in response to 40-ms voltage pulses from -180 to +100 mV in the absence of external Na+ were subtracted from current records obtained under Na+/Na+ exchange conditions. Na+-sensitive transient current and dihydroouabain-sensitive current were equivalent. The quantity of charge moved (Q) and the relaxation rate coefficient (ktot) of the slow component of the Nao+-sensitive transient current were measured for steps to various voltages (V). The data were analyzed using a four-state kinetic model describing the Na+ binding, occlusion, conformational change, and release steps of the transport cycle. The apparent valence of the Q vs. V relationship was near 1.0 for all experimental conditions. When extracellular Na+ was halved, the midpoint voltage of the charge distribution (Vq) shifted -25.3+/-0.4 mV, which can be accounted for by the presence of an extracellular ion-well having a dielectric distance delta=0.69+/-0.01. The effect of changes of Nai+ on Nao+-sensitive transient current was investigated. The midpoint voltage (Vq) of the charge distribution curve was not affected over the Nao+ concentration range 3.13-50 mM. As Nai+ was decreased, the amount of charge measured and its relaxation rate coefficient decreased with an apparent Km of 3.2+/-0.2 mM. The effects of lowering Nai+ on pre-steady-state transient current can be accounted for by decreasing the charge available to participate in the fast extracellular Na+ release steps, by a slowly equilibrating (phosphorylation/occlusion) step intervening between intracellular Na+ binding and extracellular Na+ release.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Holmgren M,Rakowski RFdoi
10.1529/biophysj.105.072942subject
Has Abstractpub_date
2006-03-01 00:00:00pages
1607-16issue
5eissn
0006-3495issn
1542-0086pii
S0006-3495(06)72350-5journal_volume
90pub_type
杂志文章abstract::The adult form of the nicotinic acetylcholine receptor (AChR) consists of five subunits (alpha(2)betaepsilondelta), each having four transmembrane domains (M1-M4). The atomic model of the nicotinic acetylcholine receptor shows that the pore-lining M2 domains make no extensive contacts with the rest of the transmembran...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.088757
更新日期:2007-01-01 00:00:00
abstract::Over the last decade, functionally designed DNA nanostructures applied to lipid membranes prompted important achievements in the fields of biophysics and synthetic biology. Taking advantage of the universal rules for self-assembly of complementary oligonucleotides, DNA has proven to be an extremely versatile biocompat...
journal_title:Biophysical journal
pub_type: 杂志文章,评审
doi:10.1016/j.bpj.2016.03.015
更新日期:2016-04-26 00:00:00
abstract::The oxygen concentration in tissue can vary on several length scales. The basic scale of variation is determined by capillary spacing. It is this scale that is manifest in the simplest Krogh cylinder model. A second, smaller scale of variation is associated with the consumption of oxygen by mitochondria. This paper gi...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(85)83856-X
更新日期:1985-12-01 00:00:00
abstract::The interaction between actin and myosin in the filament array of glycerinated muscle fibers has been monitored using paramagnetic probes and mechanical measurements. Both fiber stiffness and the spectra of probes bound to a reactive sulfydral on the myosin head were measured as the actomyosin bond was weakened by add...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(88)83136-9
更新日期:1988-04-01 00:00:00
abstract::Alterations in bone tissue composition during osteoporosis likely disrupt the mechanical environment of bone cells and may thereby initiate a mechanobiological response. It has proved challenging to characterize the mechanical environment of bone cells in vivo, and the mechanical environment of osteoporotic bone cells...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2015.02.031
更新日期:2015-04-07 00:00:00
abstract::We use optical tweezers microrheology and fluorescence microscopy to apply nonlinear microscale strains to entangled and cross-linked actin networks, and measure the resulting stress and actin filament deformations. We couple nonlinear stress response and relaxation to the velocities and displacements of individual fl...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2017.01.012
更新日期:2017-10-03 00:00:00
abstract::The microsecond folding and unfolding kinetics of ovine prion proteins (ovPrP) were measured under various solution conditions. A fragment comprising residues 94-233 of the full-length ovPrP was studied for four variants with differing susceptibilities to classical scrapie in sheep. The observed biexponential unfoldin...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.07.024
更新日期:2011-09-07 00:00:00
abstract::Atomic force microscopy (AFM) is nowadays frequently applied to determine interaction forces between biological molecules. Starting with the detection of the first discrete unbinding forces between ligands and receptors by AFM only several years ago, measurements have become more and more quantitative. At the same tim...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(00)76559-3
更新日期:2000-12-01 00:00:00
abstract::The interactions of the hydrophobic pulmonary surfactant proteins SP-B and SP-C with 1,2-dipalmitoylphosphatidylcholine in mixed, spread monolayer films have been studied in situ at the air/water interface with the technique of external reflection absorption infrared spectroscopy (IRRAS). SP-C has a mostly alpha-helic...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(95)80124-4
更新日期:1995-12-01 00:00:00
abstract::Glutamic acid [(L-glu)n] + dihydrogen phosphate systems are studied by infrared (IR) spectroscopy dried and hydrated at 75% relative humidity, as a function of both the phosphate-glutamic acid residue (Pi/glu) ratio and the type of cations present. It is shown that the glutamic acid groups form hydrogen-bonded chains ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(87)83300-3
更新日期:1987-12-01 00:00:00
abstract::The effect of ionic strength on the macroscopic and microscopic redox potentials and the heme environment of cytochrome c3 from Desulfovibrio vulgaris Miyazaki F have been investigated by NMR and electrochemical methods. The redox potentials of this tetraheme protein are found to be ionic strength-dependent. Especiall...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(98)74067-6
更新日期:1998-09-01 00:00:00
abstract::Multiplex hybridization reactions of perfectly matched duplexes and duplexes containing a single basepair mismatch (SNPs) were investigated on DNA microarrays. Effects of duplex length, G-C percentage, and relative position of the SNP on duplex hybridization and SNP resolution were determined. Our theoretical model of...
journal_title:Biophysical journal
pub_type: 信件
doi:10.1529/biophysj.107.105320
更新日期:2007-05-15 00:00:00
abstract::Reverberating spontaneous synchronized brain activity is believed to play an important role in neural information processing. Whether and how external stimuli can influence this spontaneous activity is poorly understood. Because periodic synchronized network activity is also prominent in in vitro neuronal cultures, we...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.107.112730
更新日期:2008-06-01 00:00:00
abstract::Activation of skeletal muscle ryanodine receptors (RyRs) by suramin and disulfonic stilbene derivatives (Diisothiocyanostilbene-2',2'-disulfonic acid (DIDS), 4,4'-dibenzamidostilbene-2,2'-disulfonic acid (DBDS),and 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS)) was investigated using planar bilayers. One reversible...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)74976-5
更新日期:2003-03-01 00:00:00
abstract::An assumption usually made when developing kinetic models for the gating of ion channels is that the transitions among the various states involved in the gating obey microscopic reversibility. If this assumption is incorrect, then the models and estimated rate constants made with the assumption would be in error. This...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(94)80458-8
更新日期:1994-07-01 00:00:00
abstract::We investigated the accessibility to protons and thiol-directed reagents of a cysteine substituted at position 338 in transmembrane segment 6 (TM6) of CFTR to test the hypothesis that T338 resides in the pore. Xenopus oocytes expressing T338C CFTR exhibited pH-dependent changes in gCl and I-V shape that were specific ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.050534
更新日期:2004-12-01 00:00:00
abstract::Although the majority of free cellular cholesterol is present in the plasma membrane, cholesterol homeostasis is principally regulated through sterol-sensing proteins that reside in the cholesterol-poor endoplasmic reticulum (ER). In response to acute cholesterol loading or depletion, there is rapid equilibration betw...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.08.042
更新日期:2013-10-15 00:00:00
abstract::The structure of dynamic states in biological networks is of fundamental importance in understanding their function. Considering the elementary reaction structure of reconstructed metabolic networks, we show how appreciation of a gradient matrix, G =dv/dx (where v is the vector of fluxes and x is the vector of concent...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2009.06.049
更新日期:2009-09-02 00:00:00
abstract::Annexins, found in most eukaryotic species, are cytosolic proteins that are able to bind negatively-charged phospholipids in a calcium-dependent manner. Annexin A4 (AnxA4) has been implicated in diverse cellular processes, including the regulation of exocytosis and ion-transport; however, its precise mechanistic role ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.02.057
更新日期:2013-05-07 00:00:00
abstract::We use molecular dynamics simulations to characterize the influence of cholesterol (Chol) on the interaction between the anticancer drug doxorubicin (DOX) and a dipalmitoyl phosphatidylcholine/Chol lipid bilayer. We calculate the potential of mean force, which gives us an estimate of the free energy barrier for DOX tr...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.06.015
更新日期:2011-07-20 00:00:00
abstract::The process of clathrin self-assembly into closed shells with the Fullerene structure is investigated. It is argued that the shell size distribution is governed by the kinetics of assembly and depends on the rate of growth controlled by the free clathrin concentration. The particularly abundant small structures--the "...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(97)78729-0
更新日期:1997-02-01 00:00:00
abstract::Octyl-beta-thioglucopyranoside (octyl thioglucoside, OTG) is a nonionic surfactant used for the purification, reconstitution, and crystallization of membrane proteins. The thermodynamic properties of the OTG-membrane partition equilibrium are not known and have been investigated here with high-sensitivity titration ca...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(97)78285-7
更新日期:1997-11-01 00:00:00
abstract::The solution-scattering profiles of macromolecules are significantly affected by the thermal motions of their atoms, especially at wide scattering angles, even when only a single conformational state is significantly populated in solution. Here it is shown that the impact thermal motions have on the molecular componen...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.02.016
更新日期:2014-04-01 00:00:00
abstract::We analyze a model based on receptor modification for the cAMP signaling system that controls aggregation of the slime mold Dictyostelium discoideum after starvation. The model takes into account both the desensitization of the cAMP receptor by reversible phosphorylation and the activation of adenylate cyclase that fo...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(87)83275-7
更新日期:1987-11-01 00:00:00
abstract::The type 2a sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA2a) plays a key role in intracellular Ca2+ regulation in the heart. We have previously shown evidence of stable homodimers of SERCA2a in heterologous cells and cardiomyocytes. However, the functional significance of the pump dimerization remains unclear. H...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2020.08.025
更新日期:2020-10-06 00:00:00
abstract::In this work we tested the hypothesis that transgenic sustained overexpression of IGF-1 prevents age-dependent decreases in charge movement and intracellular Ca(2+) in skeletal muscle fibers. To this end, short flexor digitorum brevis (FDB) muscle fibers from 5-7- and 21-24-month-old FVB (wild-type) and S1S2 (IGF-1 tr...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(02)75489-1
更新日期:2002-03-01 00:00:00
abstract::Neurons communicate by releasing neurotransmitters that are stored in intracellular vesicular compartments. PC12 cells are frequently used as a model secretory cell line that is described to have two subpools of vesicles: small clear vesicles and dense core vesicles. We measured transmitter molecules released from ves...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.10.060
更新日期:2014-12-16 00:00:00
abstract::Competitive hybridization, at the surface and in the bulk, lowers the sensitivity of DNA chips. Competitive surface hybridization occurs when different targets can hybridize with the same probe. Competitive bulk hybridization takes place when the targets can hybridize with free complementary chains in the solution. Th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(04)74150-8
更新日期:2004-02-01 00:00:00
abstract::The regulated ability of integrin alphaIIbbeta3 to bind fibrinogen plays a crucial role in platelet aggregation and hemostasis. We have developed a model system based on laser tweezers, enabling us to measure specific rupture forces needed to separate single receptor-ligand complexes. First of all, we performed a thor...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.061887
更新日期:2005-10-01 00:00:00
abstract::Entropy Sampling Monte Carlo (ESMC) simulations were carried out to study the thermodynamics of the folding transition in the GCN4 leucine zipper (GCN4-lz) in the context of a reduced model. Using the calculated partition functions for the monomer and dimer, and taking into account the equilibrium between the monomer ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(99)76872-4
更新日期:1999-07-01 00:00:00