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Related Concept Videos

Fusion of Secretory Vesicles with the Plasma Membrane01:26

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Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
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Pore Size Distribution01:23

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In concrete, the pore size distribution significantly influences the material's properties. Capillary pores, markedly larger than gel pores, form a vast network within partially hydrated cement paste, reducing the concrete's strength and increasing its permeability. This heightened permeability leads to a greater risk of damage from environmental factors like freeze-thaw cycles and chemical attacks, with the extent of vulnerability also being tied to the water-to-cement ratio.
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SNAREs and Membrane Fusion01:43

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Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
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Enlargement of the Plasma Membrane01:22

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Cell division and enlargement are processes that require precise control. The control ensures that cell division cannot proceed unless the cell has grown to a specific size. A spherical, dividing cell requires an approximately 1.6X increase in its surface area to double its volume. The secretory pathway also has a significant role in cell membrane enlargement. Secretory vesicles that bud off from the Golgi apparatus and later fuse with the plasma membrane during exocytosis are a major source of...
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Porin Insertion in the Outer Mitochondrial Membrane01:12

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Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
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Structure of Porins01:21

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Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
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Related Experiment Video

Updated: Mar 12, 2026

Confocal Microscopy to Measure Three Modes of Fusion Pore Dynamics in Adrenal Chromaffin Cells
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Confocal Microscopy to Measure Three Modes of Fusion Pore Dynamics in Adrenal Chromaffin Cells

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How large is a fusion pore?

Meyer B Jackson1

  • 1Department of Neuroscience, University of Wisconsin - Madison, Madison, Wisconsin.

Biophysical Journal
|March 11, 2026
PubMed
Summary
This summary is machine-generated.

This study clarifies fusion pore size measurements in exocytosis. Reconciling divergent results, it suggests flux-based methods may underestimate initial fusion pore diameter, highlighting biologically relevant variations.

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SNARE-mediated Fusion of Single Proteoliposomes with Tethered Supported Bilayers in a Microfluidic Flow Cell Monitored by Polarized TIRF Microscopy
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Fine-tuning the Size and Minimizing the Noise of Solid-state Nanopores
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Area of Science:

  • Cell Biology
  • Biophysics

Background:

  • The fusion pore is critical for understanding exocytosis and membrane fusion mechanisms.
  • Estimating fusion pore diameter is challenging, with current methods yielding widely divergent results.

Purpose of the Study:

  • To critically assess methods for determining fusion pore diameter.
  • To reconcile discrepancies in fusion pore size estimates and identify a fundamental structure.

Main Methods:

  • Review and assessment of structural and physiological techniques for fusion pore diameter estimation.
  • Analysis of flux measurement models, particularly the cylindrical pore model.

Main Results:

  • Flux-based diameter estimates may systematically underestimate the actual pore size.
  • Focusing on the initial fusion pore state reveals a distinct structure.
  • Accounting for modeling limitations narrows the range of initial fusion pore sizes.

Conclusions:

  • Disparities in fusion pore size estimates can be reduced by critical assessment of methods.
  • Initial fusion pore size likely exhibits biologically significant variations.