Is a membrane tether required for vesicle tethering to Golgi. Has an essential role in the maintenance of Golgi structure and function (PubMed:25473115, PubMed:30728324). It is required for efficient anterograde and retrograde trafficking in the early secretory pathway, functioning at both the ER-to-Golgi intermediate compartment (ERGIC) and Golgi complex (PubMed:25717001). Binds the ligand binding domain of the thyroid receptor (THRB) in the presence of triiodothyronine and enhances THRB-modulated transcription.