Molecular and Cellular Biochemistry

, Volume 326, Issue 1–2, pp 9–13 | Cite as

Yeast oxysterol-binding proteins: sterol transporters or regulators of cell polarization?

  • Christopher T. Beh
  • Gabriel Alfaro
  • Giselle Duamel
  • David P. Sullivan
  • Michael C. Kersting
  • Shubha Dighe
  • Keith G. Kozminski
  • Anant K. Menon


Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) are a conserved family of soluble cytoplasmic proteins that can bind sterols, translocate between membrane compartments, and affect sterol trafficking. These properties make ORPs attractive candidates for lipid transfer proteins (LTPs) that directly mediate nonvesicular sterol transfer to the plasma membrane. To test whether yeast ORPs (the Osh proteins) are sterol LTPs, we studied endoplasmic reticulum (ER)-to-plasma membrane (PM) sterol transport in OSH deletion mutants lacking one, several, or all Osh proteins. In conditional OSH mutants, ER-PM ergosterol transport slowed ~20-fold compared with cells expressing a full complement of Osh proteins. Although this initial finding suggested that Osh proteins act as sterol LTPs, the situation is far more complex. Osh proteins have established roles in Rho small GTPase signaling. Osh proteins reinforce cell polarization and they specifically affect the localization of proteins involved in polarized cell growth such as septins, and the GTPases Cdc42p, Rho1p, and Sec4p. In addition, Osh proteins are required for a specific pathway of polarized secretion to sites of membrane growth, suggesting that this is how Osh proteins affect Cdc42p- and Rho1p-dependent polarization. Our findings suggest that Osh proteins integrate sterol trafficking and sterol-dependent cell signaling with the control of cell polarization.


Oxysterol-binding proteins Cholesterol Nonvesicular sterol transport Saccharomyces cerevisiae OSH genes Cell polarization Rho small GTPases 



Endoplasmic reticulum


Green-fluorescent protein


Lipid transfer protein


Oxysterol-binding protein related protein


Oxysterol-binding protein


Plasma membrane



Research funding is provided to Christopher T. Beh by a grant from The Natural Science and Engineering Research Council of Canada (NSERC) and by joint contributions from the Canadian Foundation for Innovation and the British Columbia Knowledge and Development Fund. K.G.K. was funded by a grant (#0723342) from the National Science Foundation.


  1. 1.
    Urbani L, Simoni RD (1990) Cholesterol and vesicular stomatitis virus G protein take separate routes from the endoplasmic reticulum to the plasma membrane. J Biol Chem 265:1919–1923PubMedGoogle Scholar
  2. 2.
    Baumann NA, Sullivan DP, Ohvo-Rekilä H et al (2005) Transport of newly synthesized sterol to the sterol-enriched plasma membrane occurs via nonvesicular equilibration. Biochemistry 44:5816–5826. doi: 10.1021/bi048296z PubMedCrossRefGoogle Scholar
  3. 3.
    Dawson PA, Van der Westhuyzen DR, Goldstein JL et al (1989) Purification of oxysterol binding protein from hamster liver cytosol. J Biol Chem 264:9046–9052PubMedGoogle Scholar
  4. 4.
    Schroepfer GJ Jr (2000) Oxysterols: modulators of cholesterol metabolism and other processes. Physiol Rev 80:361–554PubMedGoogle Scholar
  5. 5.
    Kandutsch AA, Taylor FR, Shown EP (1984) Different forms of the oxysterol-binding protein. Binding kinetics and stability. J Biol Chem 259:12388–12397PubMedGoogle Scholar
  6. 6.
    Im YJ, Raychaudhuri S, Prinz WA et al (2005) Structural mechanism for sterol sensing and transport by OSBP-related proteins. Nature 437:154–158. doi: 10.1038/nature03923 PubMedCrossRefGoogle Scholar
  7. 7.
    Levine TP, Munro S (2002) Targeting of Golgi-specific pleckstrin homology domains involves both PtdIns 4-kinase-dependent and- independent components. Curr Biol 12:695–704. doi: 10.1016/S0960-9822(02)00779-0 PubMedCrossRefGoogle Scholar
  8. 8.
    Li X, Rivas MP, Fang M et al (2002) Analysis of oxysterol binding protein homologue Kes1p function in regulation of Sec14p-dependent protein transport from the yeast Golgi complex. J Cell Biol 157:63–77. doi: 10.1083/jcb.200201037 PubMedCrossRefGoogle Scholar
  9. 9.
    Fairn GD, Curwin AJ, Stefan CJ et al (2007) The oxysterol binding protein Kes1p regulates Golgi apparatus phosphatidylinositol-4-phosphate function. Proc Natl Acad Sci USA 104:15352–15357. doi: 10.1073/pnas.0705571104 PubMedCrossRefGoogle Scholar
  10. 10.
    Perry RJ, Ridgway ND (2006) Oxysterol-binding protein and vesicle-associated membrane protein-associated protein are required for sterol-dependent activation of the ceramide transport protein. Mol Biol Cell 17:2604–2616. doi: 10.1091/mbc.E06-01-0060 PubMedCrossRefGoogle Scholar
  11. 11.
    Wang PY, Weng J, Anderson RG (2005) OSBP is a cholesterol-regulated scaffolding protein in control of ERK 1/2 activation. Science 307:1472–1476. doi: 10.1126/science.1107710 PubMedCrossRefGoogle Scholar
  12. 12.
    Sugawara K, Morita K, Ueno N et al (2001) BIP, a BRAM-interacting protein involved in TGF-beta signalling, regulates body length in Caenorhabditis elegans. Genes Cells 6:599–606. doi: 10.1046/j.1365-2443.2001.00444.x PubMedCrossRefGoogle Scholar
  13. 13.
    Lessmann E, Ngo M, Leitges M et al (2007) Oxysterol-binding protein-related protein (ORP) 9 is a PDK-2 substrate and regulates Akt phosphorylation. Cell Signal 19:384–392. doi: 10.1016/j.cellsig.2006.07.009 PubMedCrossRefGoogle Scholar
  14. 14.
    Kozminski KG, Alfaro G, Dighe S et al (2006) Homologues of Oxysterol-binding proteins affect Cdc42p- and Rho1p-mediated cell polarization in Saccharomyces cerevisiae. Traffic 7:1224–1242. doi: 10.1111/j.1600-0854.2006.00467.x PubMedCrossRefGoogle Scholar
  15. 15.
    Jiang B, Brown JL, Sheraton J et al (1994) A new family of yeast genes implicated in ergosterol synthesis is related to the human oxysterol binding protein. Yeast 10:341–353. doi: 10.1002/yea.320100307 PubMedCrossRefGoogle Scholar
  16. 16.
    Schmalix WA, Bandlow W (1994) Swh1 from yeast encodes a candidate nuclear factor containing ankyrin repeats and showing homology to mammalian oxysterol-binding protein. Biochim Biophys Acta 1219:205–210PubMedGoogle Scholar
  17. 17.
    Beh CT, Cool L, Phillips J et al (2001) Overlapping functions of the yeast Oxysterol-binding protein homologues. Genetics 157:1117–1140PubMedGoogle Scholar
  18. 18.
    Jaworski CJ, Moreira E, Li A et al (2001) A family of 12 human genes containing oxysterol-binding domains. Genomics 78:185–196. doi: 10.1006/geno.2001.6663 PubMedCrossRefGoogle Scholar
  19. 19.
    Lehto M, Laitinen S, Chinetti G et al (2001) The OSBP-related protein family in humans. J Lipid Res 42:1203–1213PubMedGoogle Scholar
  20. 20.
    Beh CT, Rine J (2004) A role for yeast Oxysterol-binding protein homologs in endocytosis and in the maintenance of intracellular sterol-lipid distribution. J Cell Sci 117:2983–2996. doi: 10.1242/jcs.01157 PubMedCrossRefGoogle Scholar
  21. 21.
    Zinser E, Sperka-Gottlieb CDM, Fasch E-V et al (1991) Phospholipid synthesis and lipid composition of subcellular membranes in the unicellular eukaryote Saccharomyces cerevisiae. J Bacteriol 173:2026–2034PubMedGoogle Scholar
  22. 22.
    Raychaudhuri S, Im YJ, Hurley JH et al (2006) Nonvesicular sterol movement from plasma membrane to ER requires oxysterol-binding protein-related proteins and phosphoinositides. J Cell Biol 173:107–119. doi: 10.1083/jcb.200510084 PubMedCrossRefGoogle Scholar
  23. 23.
    Olkkonen VM, Levine TP (2004) Oxysterol binding proteins: in more than one place at one time? Biochem Cell Biol 82:87–98. doi: 10.1139/o03-088 PubMedCrossRefGoogle Scholar
  24. 24.
    Kvam E, Goldfarb DS (2004) Nvj1p is the outer-nuclear-membrane receptor for oxysterol-binding protein homolog Osh1p in Saccharomyces cerevisiae. J Cell Sci 117:4959–4968. doi: 10.1242/jcs.01372 PubMedCrossRefGoogle Scholar
  25. 25.
    Harsay E, Bretscher A (1995) Parallel secretory pathways to the cell surface in yeast. J Cell Biol 131:297–310. doi: 10.1083/jcb.131.2.297 PubMedCrossRefGoogle Scholar
  26. 26.
    Munson M, Novick P (2006) The exocyst defrocked, a framework of rods revealed. Nat Struct Mol Biol 13:577–581. doi: 10.1038/nsmb1097 PubMedCrossRefGoogle Scholar
  27. 27.
    Johansson M, Rocha N, Zwart W et al (2007) Activation of endosomal dynein motors by stepwise assembly of Rab7-RILP-p150Glued, ORP1L, and the receptor βlll spectrin. J Cell Biol 176:459–471. doi: 10.1083/jcb.200606077 PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC. 2008

Authors and Affiliations

  • Christopher T. Beh
    • 1
  • Gabriel Alfaro
    • 1
  • Giselle Duamel
    • 1
  • David P. Sullivan
    • 2
  • Michael C. Kersting
    • 2
  • Shubha Dighe
    • 3
  • Keith G. Kozminski
    • 3
  • Anant K. Menon
    • 2
  1. 1.Department of Molecular Biology & BiochemistrySimon Fraser UniversityBurnabyCanada
  2. 2.Department of BiochemistryWeill Cornell Medical CollegeNew YorkUSA
  3. 3.Departments of Biology & Cell BiologyUniversity of VirginiaCharlottesvilleUSA

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