title: p28, a novel ERGIC/cis Golgi protein, required for Golgi ribbon formation.
abstract: The mammalian Golgi apparatus consists of individual cisternae that are stacked in a polarized manner to form the compact zones of the Golgi. Several stacks are linked to form a ribbon via dynamic lateral bridges. The determinants required for maintaining the characteristic Golgi structure are incompletely understood. Here, we have characterized p28, a new gamma-subfamily member of p24 membrane proteins. p28 localized to endoplasmic reticulum-Golgi intermediate compartment (ERGIC) and cis Golgi and accumulated in the ERGIC upon Brefeldin A treatment, typical for a protein cycling in the early secretory pathway. p28 interacted with a subset of p24 proteins. Its depletion by small interfering RNA (siRNA) led to fragmentation of the Golgi without affecting the overall organization of microtubules but considerably reducing the amount of acetylated tubulin. The distribution of COPI and tethers, including GM130, was not affected. At the ultrastructural level, the Golgi fragments appeared as mini-stacks with apparently unchanged cis-trans topology. Golgi fragmentation did not impair anterograde or retrograde traffic. Fluorescence recovery after photobleaching (FRAP) experiments revealed that silencing p28 prevents protein exchange between Golgi stacks during reassembly after Brefeldin A-induced Golgi breakdown. These results show that the formation of a Golgi ribbon requires the structural membrane protein p28 in addition to previously identified SNAREs, coat proteins and tethers.
authors: Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
authors: Eva
authors: E
authors: Koegler
authors: Carine
authors: C
authors: Bonnon
authors: Lorenz
authors: L
authors: Waldmeier
authors: Sandra
authors: S
authors: Mitrovic
authors: Regula
authors: R
authors: Halbeisen
authors: Hans-Peter
authors: HP
authors: Hauri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure*; D036681:Fluorescence Recovery After Photobleaching; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure*; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D021122:Protein Subunits; D021381:Protein Transport; D016415:Sequence Alignment
chemical_list: D008565:Membrane Proteins; D021122:Protein Subunits