Acts as essential 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. Possesses ATPase activity. Component of the conserved oligomeric Golgi (COG or Sec34/Sec35) complex which consists of eight different proteins COG1-COG8. Present with 1620 molecules/cell in log phase SD medium. Belongs to the COG4 family.