The COG complex comprises eight proteins COG1-8. The COG complex plays critical roles in Golgi structure and function. The proposed function of the complex is to mediate the initial physical contact between transport vesicles and their membrane targets. A comparable role in tethering vesicles has been suggested for at least six additional large multisubunit complexes, including the exocyst, a complex that mediates trafficking to the plasma membrane. COG2 structure reveals a six-helix bundle with few conserved surface features but a general resemblance to recently determined crystal structures of four different exocyst subunits. These bundles inCOG2 may act as platforms for interaction with other trafficing proteins including SNAREs (soluble N-ethylmaleimide factor attachment protein receptors) and Rabs.