The human PSMA5 exists mainly as tetramer.PSMA5 protein is associated with conjugated linoleic acid (CLA) biosynthesis in mammary tissue.Proteasome (prosome, macropain) subunit alpha type 5 (PSMA5) was upregulated, whereas peroxiredoxin-1 and translationally controlled tumor protein 1 were downregulated in TVA-treated animals compared with the vehicle-injected controls. PSMA5 is highly expressed in goat mammary tissue and bovine mammary epithelial cells when TVA is converted into CLA.