title: Coatomer is essential for retrieval of dilysine-tagged proteins to the endoplasmic reticulum.
abstract: Dilysine motifs in cytoplasmic domains of transmembrane proteins are signals for their continuous retrieval from the Golgi back to the endoplasmic reticulum (ER). We describe a system to assess retrieval to the ER in yeast cells making use of a dilysine-tagged Ste2 protein. Whereas retrieval was unaffected in most sec mutants tested (sec7, sec12, sec13, sec16, sec17, sec18, sec19, sec22, and sec23), a defect in retrieval was observed in previously characterized coatomer mutants (sec21-1, sec27-1), as well as in newly isolated retrieval mutants (sec21-2, ret1-1). RET1 was cloned by complementation and found to encode the alpha subunit of coatomer. While temperature-sensitive for growth, the newly isolated coatomer mutants exhibited a very modest defect in secretion at the nonpermissive temperature. Coatomer from beta'-COP (sec27-1) and alpha-COP (ret1-1) mutants, but not from gamma-COP (sec21) mutants, had lost the ability to bind dilysine motifs in vitro. Together, these results suggest that coatomer plays an essential role in retrograde Golgi-to-ER transport and retrieval of dilysine-tagged proteins back to the ER.
authors.affiliation: Basel Institute for Immunology, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Letourneur
authors.forename: E C
authors.initials: EC
authors.lastname: Gaynor
authors.forename: S
authors.initials: S
authors.lastname: Hennecke
authors.forename: C
authors.initials: C
authors.lastname: Démollière
authors.forename: R
authors.initials: R
authors.lastname: Duden
authors.forename: S D
authors.initials: SD
authors.lastname: Emr
authors.forename: H
authors.initials: H
authors.lastname: Riezman
authors.forename: P
authors.initials: P
authors.lastname: Cosson
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport / Q000502:physiology; D020756:Coatomer Protein; D004151:Dipeptides; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D006602:Hexosyltransferases; D008565:Membrane Proteins / Q000378:metabolism* / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D021382:Protein Sorting Signals / Q000502:physiology; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014157:Transcription Factors; D014166:Transferases / Q000378:metabolism
chemical_list: D020756:Coatomer Protein; D004151:Dipeptides; D005656:Fungal Proteins; D008565:Membrane Proteins; D021382:Protein Sorting Signals; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C024575:lysyllysine; D014166:Transferases; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase