title: OSBP-related protein 11 (ORP11) dimerizes with ORP9 and localizes at the Golgi-late endosome interface.
abstract: We characterize here ORP11, a member of the oxysterol-binding protein family. ORP11 is present at highest levels in human ovary, testis, kidney, liver, stomach, brain, and adipose tissue. Immunohistochemistry demonstrates abundant ORP11 in the epithelial cells of kidney tubules, testicular tubules, caecum, and skin. ORP11 in HEK293 cells resides on Golgi complex and LE, co-localizing with GFP-Rab9, TGN46, GFP-Rab7, and a fluorescent medial-trans-Golgi marker. Under electron microscopic observation, cells overexpressing ORP11 displayed lamellar lipid bodies associated with vacuolar structures or the Golgi complex, indicating a disturbance of lipid trafficking. N-terminal fragment of ORP11 (aa 1-292) localized partially to Golgi, but displayed enhanced localization on Rab7- and Rab9-positive LE, while the C-terminal ligand-binding domain (aa 273-747) was cytosolic, demonstrating that the membrane targeting determinants are N-terminal. Yeast two-hybrid screen revealed interaction of ORP11 with the related ORP9. The interacting region was delineated within aa 98-372 of ORP9 and aa 154-292 of ORP11. Overexpressed ORP9 was able to recruit EGFP-ORP11 to membranes, and ORP9 silencing inhibited ORP11 Golgi association. The results identify ORP11 as an OSBP homologue distributing at the Golgi-LE interface and define the ORP9-ORP11 dimer as a functional unit that may act as an intracellular lipid sensor or transporter.
authors.affiliation: Minerva Foundation Institute for Medical Research, Biomedicum 2U, and National Institute for Health and Welfare/Public Health Genomics Unit, Biomedicum 1, FI-00290, Helsinki, Finland.
authors.forename: You
authors.initials: Y
authors.lastname: Zhou
authors.forename: Shiqian
authors.initials: S
authors.lastname: Li
authors.forename: Mikko I
authors.initials: MI
authors.lastname: Mäyränpää
authors.forename: Wenbin
authors.initials: W
authors.lastname: Zhong
authors.forename: Nils
authors.initials: N
authors.lastname: Bäck
authors.forename: Daoguang
authors.initials: D
authors.lastname: Yan
authors.forename: Vesa M
authors.initials: VM
authors.lastname: Olkkonen
mesh_terms: D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D020868:Gene Silencing; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008055:Lipids / Q000737:chemistry; D009928:Organ Specificity; D010716:Phosphatidylinositols / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011987:Receptors, Steroid / Q000737:chemistry / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure; D000098825:Oxysterol Binding Proteins
chemical_list: D008055:Lipids; D010716:Phosphatidylinositols; D011987:Receptors, Steroid; C485184:enhanced green fluorescent protein; D000098825:Oxysterol Binding Proteins; D049452:Green Fluorescent Proteins