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Alzheimer amyloid-beta peptide forms denaturant-resistant complex with type epsilon 3 but not type epsilon 4 isoform
Z Zhou1, J D Smith, P Greengard
1Laboratory of Alzheimer Research, Cornell University Medical College, New York, NY 10021, USA.
Background:
The apolipoprotein E (apoE) type epsilon 4 isoform specifies increased cerebral and cerebrovascular accumulation of amyloid-beta protein (A beta) and contributes to the genetic susceptibility underlying a large proportion (approximately 60%) of typical, sporadic Alzheimer disease. Unfortunately, in vitro biochemical studies of direct apoE isoform-specific interactions with A beta have been inconsistent, perhaps due to the use by different research groups of apoE isoform preparations in different conformational states (purified denatured versus native).
Materials And Methods:
In the current study, we have investigated the possibility that synthetic A beta(1-40) preferentially associates with native apoE of either the type epsilon 3 or the type epsilon 4 isoform.
Results:
Here, we demonstrate the preferential association of synthetic A beta(1-40) with native apoE epsilon 3. The complex between apoE epsilon 3 and A beta(1-40) could not be disrupted by sodium dodecyl sulfate. In a parallel assay, no denaturant-resistant association of A beta(1-40) with apoE epsilon 4 was detectable.
Conclusions:
These results support the notion that the apoE epsilon 4 isoform may foster beta-amyloidogenesis because apoE epsilon 4 is inefficient in forming complexes with A beta.