The intracellular dynamic of protein palmitoylation

Salaun, Christine; Greaves, Jennifer; Chamberlain, Luke H.

The progressive pattern of localization of microinjected Ras (i.e., dispersed → Golgi → plasma membrane) was also observed for semisynthetic constructs in which the N terminus of N-Ras (1-181) was ligated to either myristoylated peptides derived from G i1 or Fyn or to the N-terminal 20 amino acids from GAP43, all of which contain palmitoylation sites. This result suggests that palmitoylation of N-Ras at the Golgi is not dependent on farnesylation per se but may instead be a common feature of peripheral palmitoylated proteins with an underlying membrane affinity. Note that GAP43 lacks any other lipid modifications and had the slowest rate of Golgi accumulation (t/2 = 29 s); this protein may bind to membranes before palmitoylation via an intrinsic weak membrane affinity (Greaves et al., , 2009a . It will be particularly interesting in follow-up studies to examine whether microinjected full-length G i1 , Fyn, and GAP43 display identical intracellular localization dynamics to the peptide sequences that were fused to N-Ras. This issue is relevant because previous work has shown that regions distant from palmitoylation sites can have a marked influence on the specificity of interaction with DHHC proteins; for example, the yeast vacuolar protein Vac8 was palmitoylated specifically by Pfa3 in vitro, but the isolated palmitoylation domain from this protein was palmitoylated by all five yeast DHHC proteins that were examined (Nadolski and Linder, 2009) .