title: Rer1p, a retrieval receptor for ER membrane proteins, recognizes transmembrane domains in multiple modes.
abstract: The yeast Golgi membrane protein Rer1p is required for the retrieval of various endoplasmic reticulum (ER) membrane proteins such as Sec12p and Sec71p to the ER. We demonstrate here that the transmembrane domain (TMD) of Sec71p, a type-III membrane protein, contains an ER localization signal, which is required for physical recognition by Rer1p. The Sec71TMD-GFP fusion protein is efficiently retrieved to the ER by Rer1p. The structural feature of this TMD signal turns out to be the spatial location of polar residues flanking the highly hydrophobic core sequence but not the whole length of the TMD. On the Rer1p side, Tyr152 residue in the 4th TMD is important for the recognition of Sec12p but not Sec71p, suggesting that Rer1p interacts with its ligands at least in two modes. Sec71TMD-GFP expressed in the Deltarer1 mutant cells is mislocalized from the ER to the lumen of vacuoles via the multivesicular body (MVB) sorting pathway. In this case, not only the presence of polar residues in the Sec71TMD but also the length of the TMD is critical for the MVB sorting. Thus, the Rer1p-dependent ER retrieval and the MVB sorting in late endosomes both watch polar residues in the TMD but in a different manner.
authors.affiliation: Molecular Membrane Biology Laboratory, Discovery Research Institute, Riken, Wako, Saitama 351-0198, Japan. satoken@postman.riken.go.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Sato
authors.forename: Miyuki
authors.initials: M
authors.lastname: Sato
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
mesh_terms: D000595:Amino Acid Sequence; D002451:Cell Compartmentation; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D049452:Green Fluorescent Proteins; D020662:Guanine Nucleotide Exchange Factors; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D020539:Sequence Analysis, Protein; D033921:Vesicular Transport Proteins
chemical_list: D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C089137:RER1 protein, S cerevisiae; D011994:Recombinant Proteins; C071239:SEC12 protein, S cerevisiae; C084842:SEC66 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D049452:Green Fluorescent Proteins