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Isolation of Labile Multi-protein Complexes by in vivo Controlled Cellular Cross-Linking and Immuno-magnetic Affinity Chromatography
Published on: March 9, 2010
Clusterin, a binding protein with a molten globule-like region
R W Bailey1, A K Dunker, C J Brown
1School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660,USA.
Biochemistry
|September 26, 2001
Summary
Clusterin, a protein abundant in Sertoli cells, exhibits promiscuous binding due to natively disordered regions. These flexible structures act as a dynamic binding site, enabling clusterin to interact with diverse molecules.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Clusterin is a secreted glycoprotein found in various tissues, notably abundant in rat Sertoli cells.
- Its precise function remains elusive but is linked to cellular injury, lipid transport, and apoptosis.
- Clusterin's known ability to bind diverse molecules suggests unique structural properties.
Purpose of the Study:
- To investigate the structural basis for clusterin's promiscuous binding activity.
- To elucidate the role of disordered regions in clusterin's molecular interactions.
Main Methods:
- Sequence analysis to identify protein structural features.
- Trypsin digestion assays to assess protein flexibility.
- Fluorescence spectroscopy using 1-anilino-8-naphthalenesulfonate (ANS) to study binding.
- Solubilization assays with bacteriorhodopsin.
Main Results:
- Sequence analysis revealed three long, natively disordered regions with putative amphipathic alpha-helices.
- These regions were sensitive to trypsin digestion, indicating flexibility.
- Clusterin's interaction with ANS resembled that of molten globular proteins.
- Binding to ANS protected certain cleavage sites within disordered regions from trypsin.
- Clusterin demonstrated biological detergent properties, solubilizing bacteriorhodopsin.
Conclusions:
- Natively disordered regions with amphipathic helices form a dynamic, molten globule-like binding site in clusterin.
- This structural feature underlies clusterin's capacity for promiscuous molecular binding.
- Clusterin may function as a biological detergent involved in cellular debris clearance.
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