Acts as component of the peripheral membrane COG complex that is involved in intra-Golgi protein trafficking. COG is located at the cis-Golgi, and regulates tethering of retrograde intra-Golgi vesicles and possibly a number of other membrane trafficking events. COG2 is required for ER to Golgi vesicle docking. Not essential for viability. Component of the conserved oligomeric Golgi (COG or Sec34/Sec35) complex which consists of eight different proteins COG1-COG8. The COG complex interacts with the Rab GTPase YPT1, the Glogi SNAREs GOS1, SEC22, SED5, VTI1 and YKT6 and the COPI coatomer subunit gamma SEC21. Present with 3270 molecules/cell in log phase SD medium.