The proteasome is a multicatalytic proteinase complex with
a highly ordered ring-shaped 20S core structure. The core structure
is composed of 4 rings of 28 non-identical subunits; 2 rings are
composed of 7 alpha subunits and 2 rings are composed of 7 beta
subunits. Proteasomes are distributed throughout eukaryotic cells
at a high concentration and cleave peptides in an
ATP/ubiquitin-dependent process in a non-lysosomal pathway. An
essential function of a modified proteasome, the immunoproteasome,
is the processing of class I MHC peptides. This gene encodes a
member of the peptidase T1A family, that is a 20S core alpha
subunit.
