title: Depalmitoylated Ras traffics to and from the Golgi complex via a nonvesicular pathway.
abstract: Palmitoylation is postulated to regulate Ras signaling by modulating its intracellular trafficking and membrane microenvironment. The mechanisms by which palmitoylation contributes to these events are poorly understood. Here, we show that dynamic turnover of palmitate regulates the intracellular trafficking of HRas and NRas to and from the Golgi complex by shifting the protein between vesicular and nonvesicular modes of transport. A combination of time-lapse microscopy and photobleaching techniques reveal that in the absence of palmitoylation, GFP-tagged HRas and NRas undergo rapid exchange between the cytosol and ER/Golgi membranes, and that wild-type GFP-HRas and GFP-NRas are recycled to the Golgi complex by a nonvesicular mechanism. Our findings support a model where palmitoylation kinetically traps Ras on membranes, enabling the protein to undergo vesicular transport. We propose that a cycle of depalmitoylation and repalmitoylation regulates the time course and sites of Ras signaling by allowing the protein to be released from the cell surface and rapidly redistributed to intracellular membranes.
authors: Department of Molecular Physiology and Biophysics and Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors: J Shawn
authors: JS
authors: Goodwin
authors: Kimberly R
authors: KR
authors: Drake
authors: Carl
authors: C
authors: Rogers
authors: Latasha
authors: L
authors: Wright
authors: Jennifer
authors: J
authors: Lippincott-Schwartz
authors: Mark R
authors: MR
authors: Philips
authors: Anne K
authors: AK
authors: Kenworthy
mesh_terms: D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002522:Chlorocebus aethiops; D003513:Cycloheximide / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D009154:Mutation; D015739:Nocodazole / Q000494:pharmacology; D010168:Palmitates / Q000378:metabolism*; D021381:Protein Transport; D015398:Signal Transduction; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D010168:Palmitates; D049452:Green Fluorescent Proteins; D003513:Cycloheximide; D018631:ras Proteins; D015739:Nocodazole