Proteasomes get by with lots of help from their friends.
Proteasomes can't do it all. It was previously known that aminopeptidases frequently degrade proteasome-generated peptides. Now it appears that another protease, tripeptidyl peptidase II (TPP II), plays a critical role in cleaving proteasomal produced peptides into shorter peptides that can then be degraded by aminopeptidases.
Yewdell
Jonathan W
JW
Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 208920 USA.
Princiotta
Michael F
MF
D000626:Aminopeptidases; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D003546:Cysteine Endopeptidases / Q000276:immunology / Q000378:metabolism*; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D009097:Multienzyme Complexes / Q000276:immunology / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D012697:Serine Endopeptidases / Q000378:metabolism*
D015395:Histocompatibility Antigens Class I; D009097:Multienzyme Complexes; D010455:Peptides; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C048001:tripeptidyl-peptidase 2; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex