This family represents the C-terminus (approximately 500 residues) of the eukaryotic coatomer alpha subunit. Coatomer (COPI) is a large cytosolic protein complex which forms a coat around vesicles budding from the Golgi apparatus. Such coatomer-coated vesicles have been proposed to play a role in many distinct steps of intracellular transport. Note that many family members also contain the pfam04053 domain.