PSMA2

The proteasome is widely recognised as the central enzyme of non lysosomal protein degradation. It is responsible for intracellular protein turnover and it is also critically involved in many regulatory processes and, in higher eukaryotes, in antigen processing. The 26S proteasome is the key enzyme of the ubiquitin/ATP dependent pathway of protein degradation. The catalytic core of this unusually large complex is formed by the 20S proteasome, a barrel shaped structure shown by electron microscopy to comprise of four rings each containing seven subunits. Based on sequence similarity, all fourteen 20S proteasomal subunit sequences may be classified into two groups, alpha and beta, each group having distinct structural and functional roles. The alpha subunits comprise the outer rings and the beta subunits the inner rings of the 20S proteasome. Observations of the eukaryotic proteasome and analysis of subunit sequences indicate that each ring contains seven different subunits (alpha7/beta7/beta7/alpha7) with a member of each sub family represented in each particle. Each subunit is located in a unique position within the alpha or beta rings. 20S Proteasomes degrade only unfolded proteins in an energy independent manner, whereas 26S proteasomes degrade native and ubiquitinylated proteins in an ATP dependent manner. The native protein substrates are recognised by subunits, some with ATP binding sites, of the outer 19S caps of the 26S proteasome.

PSMA2; proteasome (prosome, macropain) subunit, alpha type, 2; proteasome subunit alpha type-2; HC3; MU; PMSA2; macropain subunit C3; proteasome subunit HC3; proteasome component C3; multicatalytic endopeptidase complex subunit C3; PSC2;