title: Retention mechanisms for ER and Golgi membrane proteins.
abstract: Unless there are mechanisms to selectively retain membrane proteins in the endoplasmic reticulum (ER) or in the Golgi apparatus, they automatically proceed downstream to the plasma or vacuole membranes. Two types of coat protein complex I (COPI)-interacting motifs in the cytosolic tails of membrane proteins seem to facilitate membrane retention in the early secretory pathway of plants: a dilysine (KKXX) motif (which is typical of p24 proteins) for the ER and a KXE/D motif (which occurs in the Arabidopsis endomembrane protein EMP12) for the Golgi apparatus. The KXE/D motif is highly conserved in all eukaryotic EMPs and is additionally present in hundreds of other proteins of unknown subcellular localization and function. This novel signal may represent a new general mechanism for Golgi targeting and the retention of polytopic integral membrane proteins.
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Caiji
authors.initials: C
authors.lastname: Gao
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Vaccine and Infectious Disease Organization, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N5E3, Canada.
authors.forename: Yejun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Byung-Ho
authors.initials: BH
authors.lastname: Kang
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Valencia, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Aniento
authors.affiliation: Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany.
authors.forename: David G
authors.initials: DG
authors.lastname: Robinson
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. Electronic address: ljiang@cuhk.edu.hk.
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D020755:Coat Protein Complex I / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D059828:Plant Cells / Q000378:metabolism; D055571:Secretory Pathway
chemical_list: D020755:Coat Protein Complex I; D008565:Membrane Proteins
keywords: COPI subpopulations; Dilysine motif; ER retrieval; Golgi retention; KXD/E motif