Abstract:
:Plexins are single-pass transmembrane receptors that bind the axon guidance molecules semaphorins. Single-pass transmembrane proteins are an important class of receptors that display a wide variety of activation mechanisms, often involving ligand-dependent dimerization or conformational changes. Resolving the activation mechanism and dimerization state of these receptors is extremely challenging, especially in a live-cell environment. Here, we report on the dimerization state of PlexinA4 and its response to activation by semaphorin binding. Semaphorins are dimeric molecules that activate plexin by binding two copies of plexin simultaneously and inducing formation of a specific active dimer of plexin. An open question is whether there are preexisting plexin dimers that could act as autoinhibitory complexes. We address these questions with pulsed interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). PIE-FCCS is a two-color fluorescence microscopy method that is directly sensitive to protein dimerization in a live-cell environment. With PIE-FCCS, we show that inactive PlexinA4 is dimerized in the live-cell plasma membrane. By comparing the cross correlation of full-length PlexinA4 to control proteins and plexin mutants, we show that dimerization of inactive PlexinA4 requires the Sema domain, but not the cytoplasmic domain. Ligand stimulation with Sema6A does not change the degree of cross correlation, indicating that plexin activation does not lead to higher-order oligomerization. Together, the results suggest that semaphorin activates plexin by disrupting an inhibitory plexin dimer and inducing the active dimer.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Marita M,Wang Y,Kaliszewski MJ,Skinner KC,Comar WD,Shi X,Dasari P,Zhang X,Smith AWdoi
10.1016/j.bpj.2015.04.043subject
Has Abstractpub_date
2015-11-03 00:00:00pages
1937-45issue
9eissn
0006-3495issn
1542-0086pii
S0006-3495(15)00940-6journal_volume
109pub_type
杂志文章abstract::The scattering and absorption coefficients of many homogeneous biological tissues such as muscle, skin, white matter in the brain, and dentin are often anisotropically oriented with respect to their bounding interface. In consequence the curves of equal intensity of re-emitted light on the surface of the slab will no ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.058305
更新日期:2005-05-01 00:00:00
abstract::Articular cartilage is the connective tissue that lines joints and provides a smooth surface for joint motion. Because cartilage is avascular, molecular transport occurs primarily via diffusion or convection, and cartilage matrix structure and composition may affect diffusive transport. Because of the inhomogeneous co...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.108.137752
更新日期:2008-11-15 00:00:00
abstract::Mathematical modeling of the cardiac action potential has proven to be a powerful tool for illuminating various aspects of cardiac function, including cardiac arrhythmias. However, no currently available detailed action potential model accurately reproduces the dynamics of the cardiac action potential and intracellula...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.98160
更新日期:2008-01-15 00:00:00
abstract::Hemolymph and protein-free hemolymph obtained from Loligo pealei were analyzed for cation concentration by the method of atomic absorption spectroscopy, for the following ions: Na+, K+, Ca++, and Mg++. No significant differences were seen in ion concentration between hemolymph and protein-free hemolymph. Of particular...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(77)85609-9
更新日期:1977-05-01 00:00:00
abstract::Molecular dynamics simulations were performed to describe the function of the ion-channel-forming toxin α-hemolysin (αHL) in lipid membranes that were composed of either 1,2-diphytanoyl-sn-glycero-3-phospho-choline or 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-choline. The simulations highlight the importance of lipid ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2018.09.009
更新日期:2018-11-06 00:00:00
abstract::Fusion of lipid bilayers proceeds via a sequence of distinct structural transformations. Its early stage involves a localized, hemifused intermediate in which the proximal but not yet the distal monolayers are connected. Whereas the so-called stalk model most successfully accounts for the properties of the hemifused i...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(02)75303-4
更新日期:2002-12-01 00:00:00
abstract::In the intestinal epithelium, proliferated epithelial cells ascend the crypts and villi and shed at the villus tips into the gut lumen. In this study, we theoretically investigate the roles of the villi on cell turnover. We present a stochastic model that focuses on the duration over which cells migrate the shortest p...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2021.01.003
更新日期:2021-01-13 00:00:00
abstract::This study reports the solid-state NMR spectroscopic characterization of the amino-proximate transmembrane domain (TM-A) of a diverged microsomal delta12-desaturase (CREP-1) in a phospholipid bilayer. A series of TM-A peptides were synthesized with 2H-labeled side chains (Ala-53, -56, and -63, Leu-62, Val-50), and the...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.067884
更新日期:2006-02-15 00:00:00
abstract::Cell spreading is involved in many physiological and pathological processes. The spreading behavior of a cell significantly depends on its microenvironment, but the biochemomechanical mechanisms of geometry-confined cell spreading remain unclear. A dynamic model is here established to investigate the spreading of cell...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2017.04.044
更新日期:2017-06-06 00:00:00
abstract::Crystals of ion-free gramicidin A (P212121: a = 24.61, b = 32.28, c = 32.52) have been investigated using neutron diffraction. A difference analysis of crystals soaked in ethanol/H2O as opposed to ethanol-d6/D2O has led to single isomorphous replacement Fourier projections of the structure at 5-A resolution. The grami...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(84)84186-7
更新日期:1984-03-01 00:00:00
abstract::Steady-state and time-resolved fluorescence spectroscopy was used to follow the local and global changes in structure and dynamics during chemical and thermal denaturation of unlabeled human serum albumin (HSA) and HSA with an acrylodan moiety bound to Cys34. Acrylodan fluorescence was monitored to obtain information ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(98)77598-8
更新日期:1998-08-01 00:00:00
abstract::We have studied tubules formed from a polymerizable lipid in aqueous dispersion using freeze-fracture replication and transmission electron microscopy. The polymerizable diacetylenic lecithin 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine converts from liposomes to hollow cylinders, which we call tubules, o...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(85)83852-2
更新日期:1985-12-01 00:00:00
abstract::The physical forces that underlie the exclusion of solutes from macromolecular surfaces can be probed in a similar way as the measurement of forces between macromolecules in condensed arrays using the osmotic stress technique and x-ray scattering. We report here the dependence of alcohol exclusion or, equivalently, th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.086579
更新日期:2006-08-01 00:00:00
abstract::It is known that the action of general anesthetics is proportional to their partition coefficient in lipid membranes (Meyer-Overton rule). This solubility is, however, directly related to the depression of the temperature of the melting transition found close to body temperature in biomembranes. We propose a thermodyn...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.099754
更新日期:2007-05-01 00:00:00
abstract::Rapid and robust methods are required to quantify the effect of hydrodynamic shear on protein conformation change. We evaluated such strategies in this work and found that the binding of the fluorescent probe 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) to hydrophobic pockets in the blood protein von ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2009.08.023
更新日期:2009-11-04 00:00:00
abstract::Deuterium NMR spectroscopy was used to study how the positioning of a dimerization motif within a transbilayer polypeptide influences its orientation and dynamics in bilayers. Three polypeptide variants comprising glycophorin A transmembrane (GpATM) dimerization motifs incorporated into lysine-terminated poly-leucine-...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.12.3725
更新日期:2011-02-02 00:00:00
abstract::This paper reports on a coupled approach to determining the structure of the gramicidin A ion channel, utilizing solid state nuclear magnetic resonance (NMR) of isotopically labeled gramicidin channels aligned parallel to the magnetic field direction, and molecular dynamics (MD). MD computations using an idealized rig...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(91)82131-2
更新日期:1991-10-01 00:00:00
abstract::We present a model of cell motility generated by actomyosin contraction of the cell cortex. We identify, analytically, dynamical instabilities of the cortex and show that they yield steady-state cortical flows, which, in turn, can induce cell migration in three-dimensional environments. This mechanism relies on the re...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.07.038
更新日期:2011-09-07 00:00:00
abstract::Nuclear calcium is a key signal in the dialogue between synapse and nucleus that controls the genomic responses required for persistent adaptations, including memory and acquired neuroprotection. The amplitude and duration of nuclear calcium transients specify activity-induced transcriptional changes. However, the pre...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.10.044
更新日期:2010-12-15 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::A model alpha-helical peptide encapsulated in a reverse micelle is used to study the structure and dynamics of proteins under constrained environments that mimic the membrane-water environment in cells. Molecular dynamics simulations of the self assembly of systems composed of a peptide, sodium bis(2-ethylhexyl) sulfo...
journal_title:Biophysical journal
pub_type: 信件
doi:10.1016/j.bpj.2009.03.014
更新日期:2009-05-20 00:00:00
abstract::Bin/Amphiphysin/Rvs-homology (BAR) domains generate and sense membrane curvature by binding the negatively charged membrane to their positively charged concave surfaces. N-BAR domains contain an N-terminal extension (helix-0) predicted to form an amphipathic helix upon membrane binding. We determined the NMR structure...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.108.134155
更新日期:2008-11-01 00:00:00
abstract::We have used chemical synthesis, electron paramagnetic resonance (EPR), and circular dichroism to detect and analyze the structural dynamics of a ryanodine receptor (RyR) peptide bound to calmodulin (CaM). The skeletal muscle calcium release channel RyR1 is activated by Ca2+-free CaM and inhibited by Ca2+-bound CaM. T...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2016.10.025
更新日期:2016-12-06 00:00:00
abstract::The absolute direction of the retinal chromophore of bacterio-rhodopsin relative to the membrane plane is investigated by using an optical second-harmonic interference technique. Compared with the known adsorbed geometry of free retinylidene Schiff base on a glass substrate, our data indicate the beta-ionone ring of t...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(89)82883-8
更新日期:1989-05-01 00:00:00
abstract::Low-power continuous-wave laser radiation is used to form a very stable microbubble at the end of a specially etched and metalized optical fiber probe. We demonstrate that the microbubble, which is firmly attached to the fiber probe, can be used to benignly trap and manipulate living swine sperm cells as well as human...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.075614
更新日期:2006-05-15 00:00:00
abstract::Cationic liposomes (CLs) are used worldwide as gene vectors (carriers) in nonviral clinical applications of gene delivery, albeit with unacceptably low transfection efficiencies (TE). We present three-dimensional laser scanning confocal microscopy studies revealing distinct interactions between CL-DNA complexes, for b...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)70055-1
更新日期:2003-05-01 00:00:00
abstract::Current methods for analysis of data from studies of protein-protein interactions using fluorescence resonance energy transfer (FRET) emerged from several decades of research using wide-field microscopes and spectrofluorometers to measure fluorescence from individual cells or cell populations. Inherent to most measure...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.01.048
更新日期:2010-05-19 00:00:00
abstract::It has recently been observed in situ in mice that insulin takes approximately 10 min to be transported 20 microm into the t-tubule networks of skeletal muscle fibers. The mechanisms for this slow transport are unknown. It has been suggested that the biochemical composition of the t-tubular space that may include larg...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.107.107888
更新日期:2007-11-01 00:00:00
abstract::Molecular machines fueled by NTP play pivotal roles in a wide range of cellular activities. One common feature among NTP-driven molecular machines is that NTP binding is a major force-generating step among the elementary reaction steps comprising NTP hydrolysis. To understand the mechanism in detail,in this study, we ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.05.016
更新日期:2014-07-01 00:00:00
abstract::On the basis of its role in the analysis of mammillary compartmental systems, a matrix with non-zero elements in the first row, first column, and along the main diagonal and with zero elements elsewhere is called a mammillary matrix. It is pointed out that such matrices occur in a variety of biological problems includ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(64)86769-2
更新日期:1964-01-01 00:00:00