title: Irradiation-induced protein inactivation reveals Golgi enzyme cycling to cell periphery.
abstract: Acute inhibition is a powerful technique to test proteins for direct roles and order their activities in a pathway, but as a general gene-based strategy, it is mostly unavailable in mammalian systems. As a consequence, the precise roles of proteins in membrane trafficking have been difficult to assess in vivo. Here we used a strategy based on a genetically encoded fluorescent protein that generates highly localized and damaging reactive oxygen species to rapidly inactivate exit from the endoplasmic reticulum (ER) during live-cell imaging and address the long-standing question of whether the integrity of the Golgi complex depends on constant input from the ER. Light-induced blockade of ER exit immediately perturbed Golgi membranes, and surprisingly, revealed that cis-Golgi-resident proteins continuously cycle to peripheral ER-Golgi intermediate compartment (ERGIC) membranes and depend on ER exit for their return to the Golgi. These experiments demonstrate that ER exit and extensive cycling of cis-Golgi components to the cell periphery sustain the mammalian Golgi complex.
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, 4400 5th Avenue, Pittsburgh, PA 15213,  USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Jarvela
authors.forename: Adam D
authors.initials: AD
authors.lastname: Linstedt
mesh_terms: D022181:COP-Coated Vesicles / Q000201:enzymology / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000528:radiation effects; D006056:Golgi Apparatus / Q000201:enzymology* / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000201:enzymology / Q000378:metabolism; D007700:Kinetics; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D011506:Proteins; D017382:Reactive Oxygen Species; C508771:killer red protein, Anthomedusae; D049452:Green Fluorescent Proteins