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Oxysterol‐binding proteins–emerging roles in cell regulation
Author(s) -
Olkkonen Vesa M.,
Zhou You,
Yan Daoguang,
Vihervaara Terhi
Publication year - 2012
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/ejlt.201200044
Subject(s) - microbiology and biotechnology , oxysterol , biology , organelle , endoplasmic reticulum , membrane contact site , cytoplasm , signal transduction , plant lipid transfer proteins , cell signaling , membrane protein , biochemistry , integral membrane protein , gene , cholesterol , membrane
Abstract Cytoplasmic oxysterol‐binding protein homologues, designated OSBP‐like (OSBPL) or OSBP‐related (ORP) proteins, constitute a family of lipid binding/transfer proteins present in a wide spectrum of eukaryotes. In mammals these proteins are encoded by 12 genes expressed ubiquitously but at different quantities in different tissue and cell types. Their unifying feature is a β‐barrel‐like ligand‐binding domain that has been shown to accommodate sterol ligands: oxysterols, cholesterol, or both, while a recent report shows that also phospholipid can be bound. Certain family members have the capacity to mediate or facilitate intracellular sterol transport or lipid exchange, while others are implicated as sterol sensors involved in cell regulation: lipid homeostatic control, signal transduction, organelle motility, or vesicle transport. Several ORPs have been localized to membrane contact sites, at which endoplasmic reticulum membranes are closely apposed with other organelles—indicating functions in the non‐vesicular transport of ions or small molecules, or in regulation of enzymatic components active at the contact sites. OSBPL gene polymorphisms are associated with cardiovascular risk factors, and altered ORP expression levels occur in certain cancers, providing the first indications of ORP involvement in human disease. In this review we summarize and analyze the latest findings concerning the function of OSBPL/ORP proteins.