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Biochem Biophys Res Commun. 1996 May 6;222(1):78-82.

Alzheimer's disease amyloid beta peptide 25-35 is localized in the membrane hydrocarbon core: x-ray diffraction analysis.

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  • 1Neurosciences Research Center, Allegheny Campus, Medical College of Pennsylvania, Pittsburgh, USA.

Abstract

Alzheimer's disease (AD) neuropathology is characterized by neuritic plaques composed primarily of amyloid beta peptide (A beta). An elevation in A beta in the cerebral cortex has been implicated in the pathophysiology of AD but its mechanism of action is unknown. The addition of A beta protein to neuronal cell cultures produces changes in the activity of various membrane proteins, including ion channels and receptors, potentially as a result of intercalating into the membrane bilayer. In this study, the interactions of the A beta fragment 25-35 [A beta(25-35)] with liposomes were directly examined by small angle x-ray diffraction approaches. One-dimensional electron density profiles generated from the diffraction data demonstrated that the addition of A beta(25-35) produced a discrete increase in electron density 0-12 A from the center of the lipid bilayer. Under these conditions, the membrane concentration of A beta(25-35) was 860-fold higher than in the aqueous buffer. These findings indicate that this peptide is highly lipophilic and inserts into the membrane hydrocarbon core. Following the intercalation of A beta(25-35) to this location in the membrane, the protein fragment may interact with regulatory membrane proteins.

PMID:
8630078
[PubMed - indexed for MEDLINE]
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