Golgi matrix protein playing a role in tethering of vesicles to Golgi membranes and in maintaining the overall structure of the Golgi apparatus. Interacts with RABH1B and RABH1C, but not with RABD1 or RABD2A. May be located to the trans-Golgi or trans-Golgi network (TGN). A number of isoforms are produced. According to EST sequences. The C-terminal domain (817-956) is necessary and sufficient for Golgi and cytoplasm targeting.