Abstract：
:In striated muscle thin filament activation is initiated by Ca(2+) binding to troponin C and augmented by strong myosin binding to actin (cross-bridge formation). Several lines of evidence have led us to hypothesize that thin filament properties may limit the level and rate of force development in cardiac muscle at all levels of Ca(2+) activation. As a test of this hypothesis we varied the cross-bridge contribution to thin filament activation by substituting 2 deoxy-ATP (dATP; a strong cross-bridge augmenter) for ATP as the contractile substrate and compared steady-state force and stiffness, and the rate of force redevelopment (k(tr)) in demembranated rat cardiac trabeculae as [Ca(2+)] was varied. We also tested whether thin filament dynamics limits force development kinetics during maximal Ca(2+) activation by comparing the rate of force development (k(Ca)) after a step increase in [Ca(2+)] with photorelease of Ca(2+) from NP-EGTA to maximal k(tr), where Ca(2+) binding to thin filaments should be in (near) equilibrium during force redevelopment. dATP enhanced steady-state force and stiffness at all levels of Ca(2+) activation. At similar submaximal levels of steady-state force there was no increase in k(tr) with dATP, but k(tr) was enhanced at higher Ca(2+) concentrations, resulting in an extension (not elevation) of the k(tr)-force relationship. Interestingly, we found that maximal k(tr) was faster than k(Ca), and that dATP increased both by a similar amount. Our data suggest the dynamics of Ca(2+)-mediated thin filament activation limits the rate that force develops in rat cardiac muscle, even at saturating levels of Ca(2+).
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Regnier M,Martin H,Barsotti RJ,Rivera AJ,Martyn DA,Clemmens Edoi
10.1529/biophysj.103.039123subject
Has Abstractpub_date
2004-09-01 00:00:00pages
1815-24issue
3eissn
0006-3495issn
1542-0086pii
S0006-3495(04)73662-0journal_volume
87pub_type
杂志文章abstract：:Understanding how polypeptides can efficiently and reproducibly attain a self-entangled conformation is a compelling biophysical challenge that might shed new light on our general knowledge of protein folding. Complex lassos, namely self-entangled protein structures characterized by a covalent loop sealed by a cystein...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2019.05.025
更新日期：2019-07-23 00:00:00
abstract：:A detailed picture of water and ion properties in small pores is important for understanding the behavior of biological ion channels. Several recent modeling studies have shown that small, hydrophobic pores exclude water and ions even if they are physically large enough to accommodate them, a mechanism called hydropho...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.105.080432
更新日期：2006-05-15 00:00:00
abstract：:Point mutations in p21ras are associated with ∼30% of human tumors by disrupting its GTP hydrolysis cycle, which is critical to its molecular switch function in cellular signaling pathways. In this work, we investigate the impact of Gln 61 substitutions in the structure of the p21N-ras active site and particularly foc...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2018.07.042
更新日期：2018-10-16 00:00:00
abstract：:39K nuclear magnetic resonance (NMR) spectra were readily obtained, in vivo, from rat muscle, kidney, and brain in 5-10 min with signal-to-noise ratios of approximately 20:1. Quantitation of the K+ signal was achieved by reference to an external standard of KCl/dysprosium nitrate as well as by reference to the proton ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(87)83332-5
更新日期：1987-02-01 00:00:00
abstract：:The refractive indices, water content, and volume of wet-spun films of Na-hyaluronate have been measured as a function of relative humidity (rh). These data are used with the Lorentz-Lorenz formula to determine the optical polarizabilities of Na-hyaluronate parallel and perpendicular to the helical axis. The analysis ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(92)81604-1
更新日期：1992-08-01 00:00:00
abstract：:Understanding the information processing ability of signal transduction pathways is of great importance because of their crucial roles in triggering various cellular responses. Despite continuing theoretical investigation, some important aspects of signal transduction such as a transient response and its connection to...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.105.070797
更新日期：2006-09-15 00:00:00
abstract：:The biophysical properties and cellular distribution of ion channels largely determine the input/output relationships of electrically excitable cells. A variety of patch pipette voltage clamp techniques are available to characterize ionic currents. However, when used by themselves, such techniques are not well suited ...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(98)78003-8
更新日期：1998-06-01 00:00:00
abstract：:A new method is presented to describe the low shear rate behavior of blood. We observed the response of a thin layer of sedimenting blood to a graded shear stress in a wedge-shaped chamber. The method allows quantitation of the degree of phase separation between red cells and plasma, and extracts the yield stress of t...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(87)83210-1
更新日期：1987-08-01 00:00:00
abstract：:A variety of experiments suggest that membrane proteins are important targets of anesthetic molecules, and that ion channels interact differently with anesthetics in their open and closed conformations. The availability of an open and a closed structural model for the KirBac1.1 potassium channel has made it possible t...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.107.119958
更新日期：2008-06-01 00:00:00
abstract：:Interactions of membrane anchored molecules such as glycolipids with a membrane surface are important in determining headgroup conformation. It is therefore essential to represent these membrane surface interactions in molecular modeling studies of glycolipids and other membrane bound molecules. We introduce here an e...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(92)81729-0
更新日期：1992-12-01 00:00:00
abstract：:We have analyzed repellent signal processing in Escherichia coli by flash photorelease of leucine from photolabile precursors. We found that 1). response amplitudes of free-swimming cell populations increased with leucine jump concentration, with an apparent Hill coefficient of 1.3 and a half-maximal dose of 14.4 micr...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.103.033043
更新日期：2004-06-01 00:00:00
abstract：:Changes in the ultraviolet light scattering from a suspension of purple membrane fragments were detected during the photocycle of bacteriorhodopsin with a cross-correlation method. The scattered light intensity from a suspension of membrane fragments containing the protein bacteriorhodopsin was measured on a logarithm...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(90)82415-2
更新日期：1990-09-01 00:00:00
abstract：:Although light microscopy and three-dimensional image analysis have made considerable progress during the last decade, it is still challenging to analyze the genome nano-architecture of specific gene domains in three-dimensional cell nuclei by fluorescence microscopy. Here, we present for the first time chromatin comp...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.104.056796
更新日期：2005-06-01 00:00:00
abstract：:The interaction with lipids of a synthetic peptide corresponding to the transmembrane domain of influenza hemagglutinin was investigated by means of electron spin resonance. A detailed analysis of the electron spin resonance spectra from spin-labeled phospholipids revealed that the major effect of the peptide on the d...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2010.11.014
更新日期：2011-01-05 00:00:00
abstract：:In this review, we focus on the early events in the process of fibroblast spreading on fibronectin matrices of different rigidities. We present a focused position piece that illustrates the many different tests that a cell makes of its environment before it establishes mature matrix adhesions. When a fibroblast is pla...
journal_title：Biophysical journal
pub_type： 杂志文章,评审
doi：10.1016/j.bpj.2014.10.041
更新日期：2014-12-02 00:00:00
abstract：:Polypeptide toxins isolated from the venom of cone snails, known as μ-conotoxins, block voltage-gated sodium channels by physically occluding the ion-conducting pathway. Using molecular dynamics, we show that one subtype of μ-conotoxins, PIIIA, effectively blocks the bacterial voltage-gated sodium channel Na(V)Ab, who...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2011.12.041
更新日期：2012-02-08 00:00:00
abstract：:We present a theory for proton diffusion through an immobilized protein membrane perfused with an electrolyte and a buffer. Using a Nernst-Planck equation for each species and assuming local charge neutrality, we obtain two coupled nonlinear diffusion equations with new diffusion coefficients dependent on the concentr...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(79)85274-1
更新日期：1979-01-01 00:00:00
abstract：:The cardiac muscle protein titin, responsible for developing passive elasticity and extensibility of muscle, possesses about 40 immunoglobulin-like (Ig) domains in its I-band region. Atomic force microscopy (AFM) and steered molecular dynamics (SMD) have been successfully combined to investigate the reversible unfoldi...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(02)75343-5
更新日期：2002-12-01 00:00:00
abstract：:Purple photosynthetic bacteria harvest light using pigment-protein complexes which are often arranged in pseudo-organelles called chromatophores. A model of a chromatophore from Rhodospirillum photometricum was constructed based on atomic force microscopy data. Molecular-dynamics simulations and quantum-dynamics calcu...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2014.04.030
更新日期：2014-06-03 00:00:00
abstract：:Computer simulations suggest that the translocation of arginine through the hydrocarbon core of a lipid membrane proceeds by the formation of a water-filled defect that keeps the arginine molecule hydrated even at the center of the bilayer. We show here that adding additional arginine molecules into one of these water...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2011.05.038
更新日期：2011-07-06 00:00:00
abstract：:We investigate the validity of continuum electrostatics in the gramicidin A channel using a recently determined high-resolution structure. The potential and electric field acting on ions in and around the channel are computed by solving Poisson's equation. These are then used in Brownian dynamics simulations to obtain...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(02)73905-2
更新日期：2002-09-01 00:00:00
abstract：:The dependences of the steady-state critical concentration and average filament length of actin solutions, on the filament branching and capping rates, are calculated using a rate methodology based on the total number of actin filaments. The methodology generalizes calculations of the "treadmilling" actin concentratio...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.105.061598
更新日期：2005-07-01 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：:Plasma insulin measurements from mice, rats, dogs, and humans indicate that insulin levels are oscillatory, reflecting pulsatile insulin secretion from individual islets. An unanswered question, however, is how the activity of a population of islets is coordinated to yield coherent oscillations in plasma insulin. Here...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2009.05.016
更新日期：2009-08-05 00:00:00
abstract：:We present the results of a detailed molecular dynamics study of the closed form of the P2X4 receptor. The fluctuations observed in the simulations were compared with the changes that occur in the transition from the closed to the open structure. To get further insight on the opening mechanism, the actual displacement...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2016.10.027
更新日期：2016-12-20 00:00:00
abstract：:We have used electron paramagnetic resonance (EPR) to probe the homo- and heterooligomeric interactions of reconstituted sarcoplasmic reticulum Ca-ATPase (SERCA) and its regulator phospholamban (PLB). SERCA is responsible for restoring calcium to the sarcoplasmic reticulum to allow muscle relaxation, whereas PLB inhib...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/j.bpj.2012.08.032
更新日期：2012-09-19 00:00:00
abstract：:Recent development of titratable coions has paved the way for realizing all-atom molecular dynamics at constant pH. To further improve physical realism, here we describe a technique in which proton titration of the solute is directly coupled to the interconversion between water and hydroxide or hydronium. We test the ...
journal_title：Biophysical journal
pub_type： 信件
doi：10.1016/j.bpj.2013.06.036
更新日期：2013-08-20 00:00:00
abstract：:Analyses of receptor-ligand interactions are important to the understanding of cellular adhesion. Traditional methods of measuring the three-dimensional (3D) dissociation constant (Kd) require at least one of the molecular species in solution and hence cannot be directly applied to the case of cell adhesion. We descri...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(98)77807-5
更新日期：1998-01-01 00:00:00
abstract：:The lipid phosphatidylinositol 4,5-bisphosphate (PIP(2)) is critical for a number of physiological functions, and its presence in membrane microdomains (rafts) appears to be important for several of these spatially localized events. However, lipids like PIP(2) that contain polyunsaturated hydrocarbon chains are usuall...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1529/biophysj.107.110536
更新日期：2008-01-01 00:00:00
abstract：:We measured the exocytotic response induced by flash photolysis of caged compounds in isolated mast cells and chromaffin cells. Vesicle fusion was measured by monitoring the cell membrane capacitance. The release of vesicular contents was followed by amperometry. In response to a GTP gamma S stimulus we found that the...
journal_title：Biophysical journal
pub_type： 杂志文章
doi：10.1016/S0006-3495(96)79315-3
更新日期：1996-08-01 00:00:00
