Claim: The proteasome (protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds) is a multicatalytic proteinase complex with a highly ordered 20S core structure is composed of four axially stacked rings of 28 non-identical subunits: the two end rings are each formed by seven alpha subunits, and the two central rings are each formed by seven beta subunits.
Evidence: Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. The proteasome is a multicatalytic proteinase complex with a highly ordered 20S core structure. This barrel-shaped core structure is composed of 4 axially stacked rings of 28 non-identical subunits: the two end rings are each formed by 7 alpha subunits, and the two central rings are each formed by 7 beta subunits.