The protein known as Cdc42 (a GTPase enzyme) regulates cell polarity and the actin cytoskeleton. In the December 25, 2008 issue of Nature, Kang et al. describe a brain isoform of Cdc42 that is regulated by reversible covalent attachment of palmitic acid to the protein. This palmitoylated isoform, dubbed Cdc42-palm concentrates in dendritic spines and has a special role in inducing these post-synaptic structures.
References:
Nature News and Views
Nature Full Article