Structure of Sterol Carrier Protein 2 at 1.8 Å Resolution Reveals a Hydrophobic Tunnel Suitable for Lipid Binding
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- 作者：Thomas Choinowski ; Helmut Hauser ; and Klaus Piontek
- 刊名：Biochemistry
- 出版年：2000
- 出版时间：February 29, 2000
- 年：2000
- 卷：39
- 期：8
- 页码：1897 - 1902
- 全文大小：559K
- 年卷期：v.39,no.8(February 29, 2000)
- ISSN：1520-4995
文摘
Sterol carrier protein 2, also known as nonspecific lipid transfer protein is a ubiquitous, small,basic protein of 13 kDa found in animals. Its primary structure is highly conserved between differentspecies, and it has been implicated in the intracellular transport of lipids and in a wide range of other invitro functions related to sterol and fatty acid metabolism. Sterol carrier protein 2 deficiency in miceleads to elevated concentrations of phytanic acid in the serum and causes hepatocarcinogenesis. However,its actual physiological role is still unknown. Although sterol carrier protein 2 has been studied extensivelyin the past 20 years, very little is known concerning its three-dimensional structure. The crystal structureof rabbit sterol carrier protein 2, determined at 1.8 Å resolution with the MIRAS method, shows a unique
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-fold. The core of this protein forms a five-stranded antiparallel -sheet flanked by five helices. AC-terminal segment (residues 114-123), together with part of the -sheet and four -helices, form ahydrophobic tunnel providing the environment for apolar ligands such as fatty acids and fatty acyl-coenzymeAs. Structurally well-characterized nonspecific lipid transfer proteins from plants have hydrophobic tunnel-like cavities, which were identified as the binding site for fatty acids and related apolar ligands. Despitethe fact that plant nonspecific lipid transfer proteins are smaller proteins than sterol carrier protein 2,show no sequence homology to sterol carier protein 2, and are structurally unrelated, the cavities of thesetwo classes of proteins are very similar with respect to size, shape, and hydrophobicity, suggesting acommon functional role.
/-fold. The core of this protein forms a five-stranded antiparallel -sheet flanked by five helices. AC-terminal segment (residues 114-123), together with part of the -sheet and four -helices, form ahydrophobic tunnel providing the environment for apolar ligands such as fatty acids and fatty acyl-coenzymeAs. Structurally well-characterized nonspecific lipid transfer proteins from plants have hydrophobic tunnel-like cavities, which were identified as the binding site for fatty acids and related apolar ligands. Despitethe fact that plant nonspecific lipid transfer proteins are smaller proteins than sterol carrier protein 2,show no sequence homology to sterol carier protein 2, and are structurally unrelated, the cavities of thesetwo classes of proteins are very similar with respect to size, shape, and hydrophobicity, suggesting acommon functional role.