COG4 is a component of the conserved oligomeric Golgi (COG) complex which mediates the proper glycosylation of proteins trafficking through the Golgi apparatus. It is included in the CATCHR (complexes associated with tethering containing helical rods) family, which includes components of the exocyst, GARP, and DSL1 complexes and share structural and functional features: the α-helical bundles at the middle/C-terminal (described as domains A-D/E) and a N-terminal coiled-coil region [, , ]. This domain is found in the middle region of COG4 and corresponds to domains B and C. Mutations in COG4 cause fatal congenital disorders of glycosylation (CDGs) in humans [, ].
