Acyl groups cycle endlessly on and off Ras to confine the protein to the Golgi and plasma membrane (PM), as shown by Oliver Rocks, Alfred Wittinghofer, Philippe Bastiaens (EMBL, Heidelberg, Germany), and colleagues.
These locales are the homes of two Ras isoforms, Nras and Hras, both of which are modified with the acyl group palmitate. Now it is shown that transport to the PM is not a one-way trip for Ras, which cycles back to the Golgi.
De- and repalmitoylation drive this cycling. Ras that could not be palmitoylated was found on all membranes. Less stable palmitates, which were more rapidly removed, favored Golgi localization. Other palmitoylated peptides cycled similarly.
The results suggest that palmitoylation occurs at the Golgi and temporarily anchors it there. Some of this pool is sent via the exocytic pathway to the PM, where the palmitate group is eventually removed. The...
