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Related Concept Videos

Mechanisms of Membrane Domain Formation00:59

Mechanisms of Membrane Domain Formation

Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Membrane Domains01:18

Membrane Domains

The membrane domains concentrate specific lipids and proteins at one place within the membrane, which helps in cell signaling, adhesion, and other critical cellular processes. These domains can differ in size, composition, function, and lifespan.
Protein Domains
The membrane comprises a group of distinct proteins responsible for carrying out a cell's specific function. For example, the plasma membrane of the human sperm, or a single germ cell, contains a unique set of proteins in the anterior...
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Assembly of the Lipid Bilayer in the ER

Biological membranes are more than just a barrier separating cell cytoplasm from the outside environment. They are highly dynamic and help maintain the integrity and physiological stability of the cells as well as membrane-bound organelles. Membranes also play vital roles in cell-to-cell and intracellular communication.
A large chunk of any biological membrane is composed of phospholipids. These lipids have a heterogeneous distribution across different subcellular organelles and even between...
Mechanisms of Membrane-bending01:15

Mechanisms of Membrane-bending

The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
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Multi-pass Transmembrane Proteins and β-barrels01:09

Multi-pass Transmembrane Proteins and β-barrels

In multi-pass transmembrane proteins, the polypeptide chain crosses the membrane more than once. The transmembrane polypeptide chain either forms an α-helix or β-strand structure. α-Helix containing multi-pass transmembrane proteins are ubiquitous, whereas β-strand containing ones are mainly found in gram-negative bacteria, mitochondria, and chloroplasts.
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
Membrane Lipids01:32

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Lipid Vesicle-mediated Affinity Chromatography using Magnetic Activated Cell Sorting (LIMACS): a Novel Method to Analyze Protein-lipid Interaction
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Lipid Vesicle-mediated Affinity Chromatography using Magnetic Activated Cell Sorting (LIMACS): a Novel Method to Analyze Protein-lipid Interaction

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Membrane channels formed by ceramide.

Marco Colombini1

  • 1Department of Biology, University of Maryland, College Park, MD 20742, USA. colombini@umd.edu

Handbook of Experimental Pharmacology
|April 13, 2013
PubMed
Summary
This summary is machine-generated.

Ceramide forms large, rigid channels in mitochondrial membranes, enabling protein transport. Bcl-2 proteins regulate these channels, influencing apoptosis.

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Area of Science:

  • Biochemistry
  • Cell Biology
  • Membrane Biophysics

Background:

  • Ceramide is a sphingolipid involved in cellular signaling and apoptosis.
  • Mitochondria play a crucial role in regulating programmed cell death (apoptosis).
  • The precise mechanism of ceramide's role in mitochondrial outer membrane permeabilization is under investigation.

Purpose of the Study:

  • To investigate the formation and properties of ceramide-induced channels in lipid and mitochondrial membranes.
  • To elucidate the role of Bcl-2 family proteins in modulating ceramide channel activity.
  • To understand the structural features of ceramide essential for channel formation and its implications in apoptosis.

Main Methods:

  • Lipid bilayer reconstitution experiments.
  • Electrophysiological recordings to characterize channel function.
  • Electron microscopy for pore visualization.
  • Use of ceramide analogs to probe structure-function relationships.
  • Studies involving Bcl-2 family proteins (Bax, Bcl-xL).

Main Results:

  • Ceramide forms large, barrel-stave channels in phospholipid/cholesterol and mitochondrial outer membranes.
  • These channels are rigid, highly organized, and approximately 10 nm in diameter.
  • Anti-apoptotic Bcl-2 proteins destabilize ceramide channels, while pro-apoptotic proteins enhance channel activity.
  • Ceramide analogs helped identify key molecular features for channel formation and interaction sites with Bax and Bcl-xL.

Conclusions:

  • Ceramide channels are key mediators of mitochondrial outer membrane permeabilization.
  • Regulation of these channels by Bcl-2 proteins is critical for controlling apoptosis.
  • Ceramide channels facilitate the release of pro-apoptotic factors from mitochondria, a central event in apoptosis.