Localization of palmitoylated and activated G protein -subunit in Dictyostelium discoideum

Guanine nucleotide-binding proteins (G proteins) act as molecular switches to regulate many fundamental cellular processes. The lipid modification, palmitoylation, can be considered as a key factor for proper G protein function and plasma membrane localization. In Dictyostelium discoidum, G2 is essential for the chemotactic response to cAMP in their developmental life cycle. However, the regulation of G2 with respect to palmitoylation, activation and G association is less clear. In this study, G2 is shown to be palmitoylated on Cys-4 by [H-3]palmitate labeling. Loss of this palmitoylation site results in redistribution of G2 within the cell and poor D. discoideum development. Cellular re-localization is also observed for activated G2. In the membrane fraction, G2-wt (YFP) is highly enriched in a low-density membrane fraction, which is palmitoylation-dependent. Activated G2 monomer and heterotrimer are shifted to two different higher-density fractions. These results broaden our understanding of how G protein localization and function are regulated inside the cells.