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. This gene encodes a member of the proteasome B-type family, also known as the T1B family, that is a 20S core beta subunit. This gene is located in the class II region of the MHC (major histocompatibility complex). Expression of this gene is induced by gamma interferon and this gene product replaces catalytic subunit 1 (proteasome beta 6 subunit) in the immunoproteasome. Proteolytic processing is required to generate a mature subunit. [provided by RefSeq, Mar 2010]
Function:
The proteasome is a multicatalytic proteinase complexwhich is characterized by its ability to cleave peptides with Arg,Phe, Tyr, Leu, and Glu adjacent to the leaving group at neutral orslightly basic pH. The proteasome has an ATP-dependent proteolyticactivity. This subunit is involved in antigen processing togenerate class I binding peptides. Replacement of PSMB6 by PSMB9increases the capacity of the immunoproteasome to cleave modelpeptides after hydrophobic and basic residues.
Subunit:
The 26S proteasome consists of a 20S proteasome core andtwo 19S regulatory subunits. The 20S proteasome core is composed of28 subunits that are arranged in four stacked rings, resulting in abarrel-shaped structure. The two end rings are each formed by sevenalpha subunits, and the two central rings are each formed by sevenbeta subunits. The catalytic chamber with the active sites is onthe inside of the barrel. This subunit is part of theimmunoproteasome where it displaces the equivalent houskeepingsubunit PSMB6. Interacts with HISLV1 TAT protein.
Subcellular Location:
Cytoplasm. Nucleus.
Tissue Specificity:
Highly expressed in immature dendritic cells (at protein level).
Post-translational modifications:
Autocleaved. The resulting N-terminal Thr residue of themature subunit is responsible for the nucleophile proteolyticactivity.
Similarity:
Belongs to the peptidase T1B family.
SWISS:
P28065
Gene ID:
5698
Database links:
Entrez Gene: 510593 Cow
Entrez Gene: 474867 Dog
Entrez Gene: 5698 Human
Entrez Gene: 16912 Mouse
Entrez Gene: 24967 Rat
Omim: 177045 Human
SwissProt: Q3SZC2 Cow
SwissProt: P28065 Human
SwissProt: P28076 Mouse
SwissProt: P28077 Rat
Unigene: 654585 Human
Unigene: 390983 Mouse
Unigene: 13686 Rat
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