The Localization of the Golgin GCC185 Is Independent of Rab6A/A′ and Arl1

Mammalian golgins of the trans-Golgi network (TGN) are small G protein effectors that are required for membrane transport and contain a Golgi targeting C-terminal GRIP domain. The localization of two TGN golgins, p230/golgin-245 and golgin-97, is mediated by the small GTPase Arl1, whereas recruitment of the TGN golgin GCC185 is controversial. Recently, GCC185 was proposed to localize to the Golgi by the co-operation of two small GTPases, Rab6A/A' and Arl1 (Burguete et al., 2008), a model based predominantly on in vitro interactions. Here we demonstrate that Golgi recruitment of endogenous GCC185 does not involve Rab6A/A' and Arl1. We find minimal colocalization between Rab6A/A' and endogenous GCC185 on Golgi membranes and failed to detect an interaction between Rab6A/A' and C-terminal domains of GCC185 by yeast two-hybrid analyses. Moreover, depletion of both Rab6A/A' and Arl1 also had no effect on the localization of endogenous GCC185 or the isolated GRIP domain of GCC185.