CATH Classification

Domain Context

CATH Clusters

Superfamily Glutamine Phosphoribosylpyrophosphate, subunit 1, domain 1
Functional Family Proteasome subunit alpha type-4

Enzyme Information

3.4.25.1
Proteasome endopeptidase complex.
based on mapping to UniProt P25156
Cleavage of peptide bonds with very broad specificity.
-!- A 20-S protein composed of 28 subunits arranged in four rings of seven. -!- The outer rings are composed of alpha subunits, but the beta subunits forming the inner rings are responsible for peptidase activity. -!- In eukaryotic organisms there are up to seven different types of beta subunits, three of which may carry the N-terminal threonine residues that are the nucleophiles in catalysis, and show different specificities. -!- The molecule is barrel-shaped, and the active sites are on the inner surfaces. -!- Terminal apertures restrict access of substrates to the active sites. -!- Inhibited by mercurial reagents and some inhibitors of serine endopeptidases. -!- Belongs to peptidase family T1. -!- Formerly EC 3.4.22.21, EC 3.4.24.5 and EC 3.4.99.46.

UniProtKB Entries (2)

Q9U8G2
Q9U8G2_9TRYP
Trypanosoma brucei
Proteasome activator protein PA26
P28061
PSB_THEAC
Thermoplasma acidophilum DSM 1728
Proteasome subunit beta

PDB Structure

PDB 1YA7
External Links
Method X-RAY DIFFRACTION
Organism Escherichia
Primary Citation
The 1.9 A structure of a proteasome-11S activator complex and implications for proteasome-PAN/PA700 interactions.
Forster, A., Masters, E.I., Whitby, F.G., Robinson, H., Hill, C.P.
Mol.Cell