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Structure. 2002 Nov;10(11):1533-40.

Crystal structure of the human supernatant protein factor.

Author information

1
Department of Chemistry and Biochemistry, University of Berne, Freiestrasse 3, Bern, Switzerland. achim.stocker@ibc.unibe.ch

Abstract

Supernatant protein factor (SPF) promotes the epoxidation of squalene catalyzed by microsomes. Several studies suggest its in vivo role in the cholesterol biosynthetic pathway by a yet unknown mechanism. SPF belongs to a family of lipid binding proteins called CRAL_TRIO, which include yeast phosphatidylinositol transfer protein Sec14 and tocopherol transfer protein TTP. The crystal structure of human SPF at a resolution of 1.9 A reveals a two domain topology. The N-terminal 275 residues form a Sec14-like domain, while the C-terminal 115 residues consist of an eight-stranded jelly-roll barrel similar to that found in many viral protein structures. The ligand binding cavity has a peculiar horseshoe-like shape. Contrary to the Sec14 crystal structure, the lipid-exchange loop is in a closed conformation, suggesting a mechanism for lipid exchange.

PMID:
12429094
DOI:
10.1016/s0969-2126(02)00884-5
[Indexed for MEDLINE]
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