Involved in the spindle assembly checkpoint. Involved in ER to Golgi vesicle-mediated transport by either facilitating USO1-dependent and -independent tethering or increasing target accuracy of fusion events of COPII-coated vesicles. Homodimer. Interacts with BUG1 (via C-terminus), probably forming a heterooligomer consisting of a GRH1 dimer and a BUG1 dimer. Interacts with COPII coat components SEC23, SEC24, SFB2 and SFB3. Localizes to cytoplasm in a punctate pattern. Association with the cis-Golgi requires N-terminal acetylation and is probably mediated via an N-terminal amphipathic helix. The localization to the Golgi is MAK3-dependent and SYS1-independent. Localizes to the Golgi together with BUG1. N-terminal acetylation; by N-terminal acetyltransferase NatC. Present with 2730 molecules/cell in log phase SD medium.