2 to 24 amino acid residues
||Bhutani N, Venkatraman P, Goldberg AL. Puromycin-sensitive aminopeptidase is the major peptidase responsible for digesting polyglutamine sequences released by proteasomes during protein degradation. EMBO J. 2007 Mar 7 26(5):1385-96. p.1385 right column bottom paragraphPubMed ID17318184
||Kisselev AF, Akopian TN, Woo KM, Goldberg AL. The sizes of peptides generated from protein by mammalian 26 and 20 S proteasomes. Implications for understanding the degradative mechanism and antigen presentation. J Biol Chem. 1999 Feb 5 274(6):3363-71.PubMed ID9920878
||P.1385 right column bottom paragraph: "In eukaryotes, ubiquitinated proteins are hydrolyzed by the 26S proteasome, an ATP-hydrolyzing complex that deubiquitinates, unfolds and translocates the substrate into the 20S catalytic chamber where proteolysis takes place (Goldberg, 2003). The 20S proteasomes digest proteins to peptides that are 2–24 residues long, two-thirds of which are shorter than nine residues (primary source). The peptides released by proteasomes are initially digested by cellular endopeptidases, especially thimet oligopeptidase (TOP), and the resulting peptides are then hydrolyzed to amino acids by aminopeptidases (Saric et al, 2004)." According to Yewdell et al. 2003 PMID 14647477 p.953 right column top paragraph "Proteasomes generate peptides that range in size from 4 to 20 amino acids (at least in vitro) (ref 6 therein, the above primary source)."