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. Alternative splicing results in multiple transcript variants encoding distinct isoforms.
1; alpha type; inter-alpha (globulin) inhibitor H2; inter-alpha (globulin) inhibitor, H2 polypeptide; inter-alpha-inhibitor heavy chain 2; Inter-alpha-trypsin inhibitor complex component II; Inter-alpha-trypsin inhibitor heavy chain H2; ITI heavy chain H2; ITI-HC2; macropain) subunit; proteasome (prosome; PSMA1; Serum-derived hyaluronan-associated protein; SHAP