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Biochem J. 1996 Jun 1;316 ( Pt 2):671-9.

Apolipoprotein J and Alzheimer's amyloid beta solubility.

Author information

1
Department of Pathology, New York University Medical Center, NY 10016, USA.

Abstract

Apolipoprotein J (apoJ) has been found associated with soluble amyloid beta (sA beta) in plasma and cerebrospinal fluid in normal individuals and co-deposited with fibrillar A beta in Alzheimer's cerebrovascular and parenchymal lesions. Although studies in vitro and in vivo indicate that apoJ is a major carrier protein for sA beta, its role in the fibrillogenesis process is not known. We report herein that apoJ in its native high-density lipoprotein lipidic environment is fully active to interact with A beta peptides. Furthermore, apoJ prevents aggregation and polymerization of synthetic A beta in vitro. The interaction was stable for at least 14 days at 37 degrees C in physiologic buffers, and the peptide retrieved after complex dissociation at low pH retained its inherent aggregation properties. In addition, the binding to apoJ protects synthetic A beta from proteolytic degradation; both A beta 1-42 and A beta 1-40 were more resistant to proteolysis by trypsin and chymotrypsin when complexed to apoJ. The data suggest that the interaction may preclude sA beta aggregation in biological fluids and point to a protecting role of apoJ for complexed A beta species.

PMID:
8687416
PMCID:
PMC1217400
DOI:
10.1042/bj3160671
[Indexed for MEDLINE]
Free PMC Article

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