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Amyloid Fibrils

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...

Mitochondrial Precursor Proteins

Mitochondrial Precursor Proteins

Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
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Translocation of Proteins into the Mitochondria

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Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...

Oligosaccharide Assembly

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Multiple sugar molecules that may or may...

Amyloid Fibrils

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...

Structure of Porins

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Related Experiment Video

Updated: Jul 21, 2026

Rapid Generation of Amyloid from Native Proteins In vitro

Rapid Generation of Amyloid from Native Proteins In vitro

Published on: December 5, 2013

The amyloid precursor protein interacts with neutral lipids.

Raghda Lahdo¹, Stéphane Coillet-Matillon, Jean-Paul Chauvet

¹Laboratoire de Physico-Chimie Biologique, Université Claude Bernard, Lyon, France.

European Journal of Biochemistry

|May 3, 2002

Summary

Amyloid precursor protein (APP) interacts with lipid membranes through electrostatic and hydrophobic forces. Membrane lipid composition significantly influences APP

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Area of Science:

Biochemistry
Molecular Biology
Membrane Biophysics

Background:

The amyloid precursor protein (APP) is a key protein implicated in Alzheimer's disease.
Understanding APP's interaction with cell membranes is crucial for elucidating its biological functions and pathological roles.
Lipid composition of membranes is known to influence the behavior of membrane-associated proteins.

Purpose of the Study:

To investigate the mechanisms by which amyloid precursor protein (APP) interacts with lipid bilayers and monolayers.
To determine the influence of lipid composition and physicochemical conditions on APP's membrane insertion and behavior.
To explore the role of electrostatic and hydrophobic interactions in APP-membrane association.

Main Methods:

Incorporation of APP into liposomes and phospholipid monolayers.
Characterization of APP's surface-active properties using monomolecular films.
Analysis of secondary structure changes using Circular Dichroism (CD) spectroscopy.

Main Results:

APP insertion into liposomes requires neutral lipids (e.g., L-alpha-phosphatidylcholine) and is hindered by acidic lipids (e.g., L-alpha-phosphatidylserine).
Acidic conditions and specific lipid head groups (electrostatic interactions) modulate APP's adsorption and penetration into lipid monolayers.
Hydrophobic interactions between APP and lipids also influence protein penetration, while APP's alpha-helical structure remains largely preserved.

Conclusions:

APP/membrane interactions are complex, mediated by both lipid composition and physicochemical factors like charge and hydrophobicity.
Variations in APP-membrane interactions are not attributed to significant changes in APP's secondary structure.
These findings provide insights into APP's partitioning into membrane microdomains and its potential role in membrane function and dysfunction.