PSMB1 (Proteasome subunit, beta type-1) encodes a member of the proteasome B-type family, also known as the T1B family, that is a 20S core beta subunit. This is tightly linked to the TBP (TATA-binding protein) gene in human and in mouse, and is transcribed in the opposite orientation in both species. The main function of PSMB1 is to degrade unnecessary or damaged proteins by proteolysis.