1c44 | pdb_00001c44
STEROL CARRIER PROTEIN 2 (SCP2) FROM RABBIT
Structural highlights
FunctionSCP2_RABIT Plays a crucial role in the peroxisomal oxidation of branched-chain fatty acids. Catalyzes the last step of the peroxisomal beta-oxidation of branched chain fatty acids and the side chain of the bile acid intermediates di- and trihydroxycoprostanic acids (DHCA and THCA) (By similarity). Also active with medium and long straight chain 3-oxoacyl-CoAs. Stimulates the microsomal conversion of 7-dehydrocholesterol to cholesterol and transfers phosphatidylcholine and 7-dehydrocholesterol between membrances, in vitro (By similarity). Isoforms SCP2 and SCPx cooperate in peroxisomal oxidation of certain naturally occurring tetramethyl-branched fatty acyl-CoAs (By similarity).[UniProtKB:P11915][UniProtKB:P22307][UniProtKB:P32020] Mediates the transfer of all common phospholipids, cholesterol and gangliosides from the endoplasmic reticulum to the plasma membrane (PubMed:9711242). May play a role in regulating steroidogenesis (By similarity). Stimulates the microsomal conversion of 7-dehydrocholesterol to cholesterol (By similarity). Also binds fatty acids and fatty acyl Coenzyme A (CoA) such as phytanoyl-CoA. Involved in the regulation phospholipid synthesis in endoplasmic reticulum enhancing the incorporation of exogenous fatty acid into glycerides. Seems to stimulate the rate-limiting step in phosphatidic acid formation mediated by GPAT3. Isoforms SCP2 and SCPx cooperate in peroxisomal oxidation of certain naturally occurring tetramethyl-branched fatty acyl-CoAs (By similarity).[UniProtKB:P11915][UniProtKB:P22307][UniProtKB:P32020][1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSterol 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 different species, and it has been implicated in the intracellular transport of lipids and in a wide range of other in vitro functions related to sterol and fatty acid metabolism. Sterol carrier protein 2 deficiency in mice leads 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 extensively in the past 20 years, very little is known concerning its three-dimensional structure. The crystal structure of rabbit sterol carrier protein 2, determined at 1.8 A resolution with the MIRAS method, shows a unique alpha/beta-fold. The core of this protein forms a five-stranded antiparallel beta-sheet flanked by five helices. A C-terminal segment (residues 114-123), together with part of the beta-sheet and four alpha-helices, form a hydrophobic tunnel providing the environment for apolar ligands such as fatty acids and fatty acyl-coenzyme As. 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. Despite the fact that plant nonspecific lipid transfer proteins are smaller proteins than sterol carrier protein 2, show no sequence homology to sterol carrier protein 2, and are structurally unrelated, the cavities of these two classes of proteins are very similar with respect to size, shape, and hydrophobicity, suggesting a common functional role. Structure of sterol carrier protein 2 at 1.8 A resolution reveals a hydrophobic tunnel suitable for lipid binding.,Choinowski T, Hauser H, Piontek K Biochemistry. 2000 Feb 29;39(8):1897-902. PMID:10684638[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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