title: The calcium-binding protein p54/NEFA is a novel luminal resident of medial Golgi cisternae that traffics independently of mannosidase II.
abstract: A new Golgi resident, p54, has been demonstrated in several eukaryotic species and in multiple organs. Based on Triton X-114 partition, carbonate extraction and trypsin protection assays, p54 behaved as an extrinsic membrane protein, facing the luminal compartment. p54 was purified by two-dimensional electrophoresis and identified by matrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) mass spectrometry as NEFA, a calcium-binding protein (Barnikol-Watanabe et al., 1994, Biol. Chem. Hoppe Seyler, 375, 497-512). By immunofluorescence, p54/NEFA essentially colocalized with the medial Golgi marker mannosidase II, and did not overlap with the cis-Golgi marker p58, nor with the trans-Golgi network (TGN) marker TGN38. By immuno-electron microscopy, p54/NEFA localized in the medial cisternae and in Golgi-associated vesicles. p54/NEFA remained associated with mannosidase II despite Golgi disruption by nocodazole, caffeine, or, to some extent, potassium depletion (a new procedure to induce Golgi disassembly), but the two markers rapidly dissociated upon brefeldin A treatment and at metaphase, and reassociated upon drug removal and at the end of anaphase. Since p54/NEFA is a peripheral luminal membrane constituent, its distinct trafficking from the transmembrane marker mannosidase II suggests a novel Golgi retention mechanism, by strong association of this soluble protein with another integral transmembrane resident.
authors.affiliation: Cell Biology Unit, Christian de Duve Institute of Cellular Pathology and Université catholique de Louvain, Brussels, Belgium.
authors.forename: Valérie M
authors.initials: VM
authors.lastname: Morel-Huaux
authors.forename: Marc
authors.initials: M
authors.lastname: Pypaert
authors.forename: Sandrine
authors.initials: S
authors.lastname: Wouters
authors.forename: Alan M
authors.initials: AM
authors.lastname: Tartakoff
authors.forename: Ulrich
authors.initials: U
authors.lastname: Jurgan
authors.forename: Kris
authors.initials: K
authors.lastname: Gevaert
authors.forename: Pierre J
authors.initials: PJ
authors.lastname: Courtoy
mesh_terms: D000818:Animals; D015415:Biomarkers; D020126:Brefeldin A; D016466:CHO Cells; D002135:Calcium-Binding Proteins; D002451:Cell Compartmentation / Q000502:physiology*; D006224:Cricetinae; D003429:Cross Reactions / Q000276:immunology; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D015180:Electrophoresis, Gel, Two-Dimensional; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D005057:Eukaryotic Cells / Q000378:metabolism* / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008361:Mannosidases / Q000378:metabolism*; D013058:Mass Spectrometry; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008938:Mitosis / Q000502:physiology; D009419:Nerve Tissue Proteins; D000080866:Nucleobindins; D011500:Protein Synthesis Inhibitors; D021381:Protein Transport / Q000502:physiology*; D051381:Rats
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; C000630652:Nucb1 protein, rat; D000080866:Nucleobindins; D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A; D008361:Mannosidases; C038829:mannosyl-oligosaccharide 1,3 - 1,6-alpha-mannosidase