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Crystal structure of the human supernatant protein factor
Achim Stocker1, Takashi Tomizaki, Clemens Schulze-Briese
1Department of Chemistry and Biochemistry, University of Berne, Freiestrasse 3, Bern, Switzerland. achim.stocker@ibc.unibe.ch
Structure (London, England : 1993)
|November 14, 2002
Summary
Supernatant protein factor (SPF), a lipid-binding protein, plays a role in cholesterol biosynthesis. Its crystal structure reveals a unique shape and a closed loop, suggesting a novel mechanism for lipid exchange in this essential pathway.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- Supernatant protein factor (SPF) is implicated in cholesterol biosynthesis.
- SPF is a member of the CRAL_TRIO family of lipid-binding proteins.
- Its precise in vivo mechanism remains to be elucidated.
Purpose of the Study:
- To determine the crystal structure of human SPF.
- To elucidate the structural basis for SPF's function in lipid binding and exchange.
Main Methods:
- X-ray crystallography at 1.9 A resolution.
- Analysis of protein domain topology and ligand-binding cavity.
Main Results:
- Human SPF exhibits a two-domain structure: a Sec14-like N-terminal domain and a C-terminal jelly-roll barrel.
- The ligand-binding cavity possesses a horseshoe-like shape.
- The lipid-exchange loop is in a closed conformation, differing from Sec14.
Conclusions:
- The determined structure provides insights into SPF's role in lipid transport.
- The closed loop conformation suggests a potential mechanism for regulated lipid exchange.
- Further studies are warranted to confirm the functional implications of the observed structure.