A5105462611- Force Microscopy Techniques and Applications
- Lipid Membrane Structure and Behavior
- Cellular transport and secretion
- Protein Structure and Dynamics
- Cellular Mechanics and Interactions
- Cardiomyopathy and Myosin Studies
- Biochemical and Structural Characterization
- Ion channel regulation and function
- Photoreceptor and optogenetics research
- Streptococcal Infections and Treatments
- Enzyme Structure and Function
- Heat shock proteins research
- RNA and protein synthesis mechanisms
- Neuroscience and Neural Engineering
- Redox biology and oxidative stress
- Microfluidic and Bio-sensing Technologies
- Molecular Junctions and Nanostructures
- Endoplasmic Reticulum Stress and Disease
- Mechanical and Optical Resonators
- Muscle Physiology and Disorders
- Monoclonal and Polyclonal Antibodies Research
- Erythrocyte Function and Pathophysiology
- Mast cells and histamine
- Toxin Mechanisms and Immunotoxins
- Receptor Mechanisms and Signaling
Columbia University
2012-2021
Mayo Clinic
1991-2000
University of Chile
1996
WinnMed
1990-1996
Centro de Estudios Científicos
1996
Mayo Clinic in Florida
1996
Stanford Medicine
1996
Scripps Research Institute
1993
University of Pennsylvania
1987-1990
Max Planck Institute for Biophysical Chemistry
1985-1987
Gating currents were measured by subtracting the linear component of capacitative current recorded at very positive or negative potentials. When membrane is depolarized for a few minutes, repolarized to usual holding potential (HP) --70 mV 1 ms, and then pulsed 0 mV, charge transferred in 2--4 ms approximately 50% that which was during same pulse mV. This decrease, called slow inactivation gating current, found be consistent with shift vs. (Q-V) curve more hyperpolarized HP total available...
Under physiological conditions, protein oxidation and misfolding occur with very low probability on long times scales. Single-molecule techniques provide the ability to distinguish between properly folded damaged proteins that are otherwise masked in ensemble measurements. However, at conditions these rare events a time constant of several hours, inaccessible current single-molecule approaches. Here we present magnetic-tweezers-based technique allows, for first time, study folding single...
Significance Mechanical signals in biology are complex and change rapidly the millisecond timescale. Current force spectroscopy instrumentation is limited to constant forces slowly changing ramps. Here we introduce a spectrometer that uses commercial tape head create magnetic field can deliver large with submillisecond time resolution. We demonstrate stability of this by measuring folding dynamics ultrasensitive talin protein its speed capturing ephemeral molten globule states L. Our...
For fusion to occur the repulsive forces between two interacting phospholipid bilayers must be reduced. In model systems, this can achieved by increasing surface tension of at least one membranes. However, there has so far been no evidence that secretory granule membrane is under tension. We have studying exocytosis using patch-clamp technique measure area plasma degranulating mast cells. When a fuses with step increase in cell area. Some events are reversible, which case we found backstep...
The ionic conductances in rat basophilic leukemia cells (RBL-2H3) and peritoneal mast were investigated using the patch-clamp technique. These two cell types found to have different electrophysiological properties resting state. only significant conductance of RBL-2H3 was a K+-selective inward rectifier. single channel at room temperature increased from 2-3 pS 2.8 mM external K+ 26 130 K+. This conductance, which appeared determine potential, could be blocked by Na+ Ba2+ voltage-dependent...
We have used the whole-cell patch-pipette technique to measure step increases in cell membrane capacitance (equivalent area) caused by fusion of secretory granules degranulating murine mast cells. observed that up 30% total expansion degranulation results from large events cannot be explained single granules. These are mainly initial phase a degranulation. developed simple mathematical model for test whether these stimulus-induced, granule-to-granule occurs before their exocytosis...
In the early stages of an infection, pathogenic bacteria use long fibrous structures known as pili adhesive anchors for attachment to host cells. These also play key roles in colony and biofilm formation. all those processes, must withstand large mechanical forces. The nasty gram-positive human pathogen Streptococcus pyogenes are assembled single, micrometer tandem modular proteins covalently linked repeats pilin proteins. Here we single molecule force spectroscopy techniques study...
Abstract Proteins fold under mechanical forces in a number of biological processes, ranging from muscle contraction to co-translational folding. As force hinders the folding transition, chaperones must play role this scenario, although their influence on protein has not been directly monitored yet. Here, we introduce single-molecule magnetic tweezers study dynamics L presence prototypical molecular chaperone trigger factor over range physiological (4–10 pN). Our results show that increases...
Significance Bacteria colonizing the oropharynx must adhere despite mechanical challenges from coughing, sneezing, and chewing; however, little is known about how Gram-positive organisms achieve this feat. We studied pilus adhesive proteins two report a conserved mechanism for dissipating energy of perturbation. The are stable up to forces 525 pN 690 pN, respectively, making these most mechanically known. After perturbation, refold rapidly at low force, resulting in large hysteresis with...
Significance Talin is an adaptor protein that transduces mechanical signals into biochemical cues by recruiting a network of ligands in force-dependent way. These force have complex nature, oscillate time with different frequency components, and are often embedded noise. However, most assays to explore the mechanics force-sensing proteins rely on simple perturbations, such as constant or ramped forces. Here, we use our magnetic tweezers design subject single talin domains oscillatory forces...
Mechanical force regulates talin-vinculin association and defines an optimal binding range.