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The chaperone action of clusterin a widely distributed and highly conserved glycoprotein found at high levels in human blood is described and characterized. Results show that there is a possibility that haptoglobin (Hp) may exert an anti-inflammatory action in vivo by inhibiting the inappropriate self-association of damaged extracellular proteins.

Research has been conducted on clusterin, the extracellular mammalian chaperone binding to the unfolded stressed proteins. The hypothesis that clusterin binds to toxic molecules in the extracellular environment and carries these to the cells expressing lipoprotein receptor-related protein-2 for the uptake and degradation has been tested and the results are reported.

Results point out that stabilization of stressed proteins by clusterin is mediated by inhibiting the rapid and irreversible protein precipitation leading to an accumulation of inactive but stabilized protein molecules. Data also show that clusterin lacks ATPase activity and ATP does not influence clusterin's ability to inhibit stress-induced precipitation.

Research has been conducted on the ligand-binding properties and structure of the human clusterin. The chaperone-like activity of this clusterin has been investigated.

Clusterin is a glycoprotein highly conserved among mammalian species and has been postulated to bind heparin. Enzyme-linked immunosorbent assay and affinity chromatography studies were undertaken to investigate this hypothesis. Results reveal that clusterin binds heparin with an affinity constant measurable in sub-micromolar levels. The affinity is enhanced at low pH levels. Denaturation studies reveal that the alpha chain of the protein is responsible for heparin binding.

Research was conducted to study the effect of clusterin expression on the regulation of cell death signals using transfected L929 cells. A series of stably transfected L929 cell lines that express human clusterin was developed and the effects of tumor necrosis factor-alpha and transforming growth factors-beta as well as other cytotoxic agents on the survival of these cells and on the biosynthesis and subcellular localization of clusterin were examined.

The interaction of histidine-rich glycoprotein (HRG) with human IgG and Clq as well as its role in the formation of insoluble immune complexes were investigated. Enzyme-linked immunosorbent assay (ELISA) and IAsys resonant mirror biosensor results have shown that physiological concentrations of HRG binds strongly to Clq and to IgG. Furthermore, HRG inhibits the formation of insoluble immune complexes (IIC).

The peptide-based ELISA test for assessing dimerization affinities of Jun and Fos protein complexes is simple, rapid and sensitive. c-Jun and c-Fos preferentially form heterodimers by using leucine zipper domains. Recombinant Jun leucine zipper peptides bind to a fosLZ-glutathione S-transferase fusion protein. Jun:Fos complexes are detected through enzyme complex amplification. This ELISA system enables the detection of subanomolar concentrations of Jun and Fos, and determination of dissociation constants for complex formation.

The effects of Cu(II), Zn(II), Al(III) and Fe(II) on amyloid formation from wild-type (WT) transthyretin as well as its V30M, L55P and T119M mutants are investigated. It is shown that Zn(II) enhanced urea-mediated dissociation of the L55P but not the WT transthyretin tetramer, whereas Cu(II), depending on its concentration, either had no effect or stabilized the WT tetramer but could only increase urea-mediated dissociation of L55P.

A technique is developed to enzymatically remove attached sugars from human serum-derived clusterin under native conditions and a series of assays is performed to compare the structure and in vitro function of wild type and deglycosylated clusterin. Evidence suggests that the normally conjugated sugars are important in the interaction of secreted clusterin with a lectin-type receptor on liver cells.