Depalmitoylated Ras traffics to and from the Golgi complex via a nonvesicular pathway.

Goodwin JS, Drake KR, Rogers C, Wright L, Lippincott-Schwartz J, Philips MR, Kenworthy AK
J Cell Biol. 2005 170 (2): 261-72

PMID: 16027222 · PMCID: PMC2171405 · DOI:10.1083/jcb.200502063

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.

MeSH Terms (16)

Animals Cell Membrane Cercopithecus aethiops COS Cells Cycloheximide Cytosol Endoplasmic Reticulum Golgi Apparatus Green Fluorescent Proteins Microtubules Mutation Nocodazole Palmitates Protein Transport ras Proteins Signal Transduction

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