Mouse prenylated Rab acceptor is a novel Golgi membrane protein

We have cloned a mouse prenylated Rab acceptor (mPRA), which interacts with various Rab proteins in the yeast two-hybrid system. This study investigated its intracellular localization and characterized the localization signal. The mPRA was found to be an integral membrane protein that was localized to the Golgi complex at steady state as determined by confocal fluorescence microscopy. With green fluorescent protein attached to the N-terminus of mPRA, the fusion protein was expressed in BHK cells and was shown to exhibit the same Golgi localization as the native mPRA. Systematic truncations from the N- and C-termini of mPRA revealed that the entire N-terminal half (91 residues) of the protein was dispensable for the Golgi localization. In contrast, deletion of only 5 residues from the C-terminus diminished the Golgi localization of mPRA, leading to its accumulation in the ER. The data indicate that the C-terminal half (94 residues) of mPRA is necessary and sufficient for proper folding, ER export, and Golgi localization. The Golgi localization of mPRA suggests that it may play a role in the structural organization and function of the Golgi complex.