This gene encodes a protein that is a component of the conserved oligomeric Golgi (COG) complex, a multiprotein complex that plays a structural role in the Golgi apparatus, and is involved in intracellular membrane trafficking and glycoprotein modification. Mutations in this gene cause congenital disorder of glycosylation, type IIh, a disease that is characterized by under-glycosylated serum proteins, and whose symptoms include severe psychomotor retardation, failure to thrive, seizures, and dairy and wheat product intolerance. [provided by RefSeq, Jul 2008].