Purity: > 90% by SDS - PAGE Format: Liquid. In 20mM Tris-HCl buffer (pH 8.0) containing 1mM DTT, 50% glycerol, 0.2M NaCl. 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.. Recombinant human PSMB3 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.