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

• Published in: The Journal of cell biology Vol. 170; no. 2; pp. 261 - 272
• Main Authors: Goodwin, J. Shawn, Drake, Kimberly R, Rogers, Carl, Wright, Latasha, Lippincott-Schwartz, Jennifer, Philips, Mark R, Kenworthy, Anne K
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 18.07.2005; The Rockefeller University Press
• Subjects: Adipocytes; Animals; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell membranes; Cellular biology; Cercopithecus aethiops; COS Cells; Cycloheximide - pharmacology; Cytosol - metabolism; Endoplasmic Reticulum - metabolism; Fluorescence; Golgi apparatus; Golgi Apparatus - metabolism; Green Fluorescent Proteins - genetics; Membranes; Microtubules - drug effects; Microtubules - metabolism; Mutation; Nocodazole - pharmacology; P branes; Palmitates; Palmitates - metabolism; Physiological regulation; Protein Transport; Proteins; ras Proteins - genetics; ras Proteins - metabolism; ras Proteins - physiology; Signal Transduction; Signaling; T lymphocytes
• ISSN: 0021-9525; 1540-8140
• 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.