title: A protein complex containing Epo1p anchors the cortical endoplasmic reticulum to the yeast bud tip.
abstract: The cortical endoplasmic reticulum (cER) of yeast underlies the plasma membrane (PM) at specific contact sites to enable a direct transfer of information and material between both organelles. During budding, directed movement of cER to the young bud followed by subsequent anchorage at its tip ensures the faithful inheritance of this organelle. The ER membrane protein Scs2p tethers the cER to the PM and to the bud tip through so far unknown receptors. We characterize Epo1p as a novel member of the polarisome that interacts with Scs2p exclusively at the cell tip during bud growth and show that Epo1p binds simultaneously to the Cdc42p guanosine triphosphatase-activating protein Bem3p. Deletion of EPO1 or deletion of BEM3 in a polarisome-deficient strain reduces the amount of cER at the tip. This analysis therefore identifies Epo1p as a novel and important component of the polarisome that promotes cER tethering at sites of polarized growth.
authors.affiliation: Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, D-89081 Ulm, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Neller
authors.affiliation: Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, D-89081 Ulm, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Dünkler
authors.affiliation: Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, D-89081 Ulm, Germany.
authors.forename: Reinhild
authors.initials: R
authors.lastname: Rösler
authors.affiliation: Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, D-89081 Ulm, Germany nils.johnsson@uni-ulm.de.
authors.forename: Nils
authors.initials: N
authors.lastname: Johnsson
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D046912:Multiprotein Complexes; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: C084220:BEM3 protein, S cerevisiae; D002352:Carrier Proteins; C000594941:Epo1 protein, S cerevisiae; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C501314:Scs2 protein, S cerevisiae