Local and substrate-specific S-palmitoylation determines subcellular localization of Gαo

Solis, Gonzalo P.; Kazemzadeh, Arghavan; Valnohova, Jana; Abrami, Laurence; Alvarez, Cecilia; van der Goot, F. Gisou; Katanaev, Vladimir L.

Peripheral membrane proteins (PMPs) associate with cellular membranes through post-translational modifications like S-palmitoylation. The Golgi apparatus is generally viewed as the transitory station where palmitoyl acyltransferases (PATs) modify PMPs, which are then transported to their ultimate destinations such as plasma membrane (PM); little substrate specificity among the many PATs has been determined. Here we describe inherent partitioning of Gαo – α-subunit of heterotrimeric Go-proteins – to PM and Golgi, independent from Golgi-to-PM transport. A minimal code within the Gαo N-terminus governs the compartmentalization and re-coding produces G-protein versions with shifted localization. We established the S-palmitoylation at the outer nuclear membrane assay (“SwissKASH”) to probe substrate specificity of PATs in intact cells. With this assay, we showed that PATs localizing to different membrane compartments display remarkable substrate selectivity, which is the basis for specific PMP compartmentalization. Our findings uncover a novel mechanism governing protein localization and establish the basis for innovative drug discovery.