1pma
From Proteopedia
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PROTEASOME FROM THERMOPLASMA ACIDOPHILUM
Overview
The three-dimensional structure of the proteasome from the archaebacterium Thermoplasma acidophilum has been elucidated by x-ray crystallographic analysis by means of isomorphous replacement and cyclic averaging. The atomic model was built and refined to a crystallographic R factor of 22.1 percent. The 673-kilodalton protease complex consists of 14 copies of two different subunits, alpha and beta, forming a barrel-shaped structure of four stacked rings. The two inner rings consist of seven beta subunits each, and the two outer rings consist of seven alpha subunits each. A narrow channel controls access to the three inner compartments. The alpha 7 beta 7 beta 7 alpha 7 subunit assembly has 72-point group symmetry. The structures of the alpha and beta subunits are similar, consisting of a core of two antiparallel beta sheets that is flanked by alpha helices on both sides. The binding of a peptide aldehyde inhibitor marks the active site in the central cavity at the amino termini of the beta subunits and suggests a novel proteolytic mechanism.
About this Structure
1PMA is a Protein complex structure of sequences from Thermoplasma acidophilum. Active as Proteasome endopeptidase complex, with EC number 3.4.25.1 Full crystallographic information is available from OCA.
Reference
Crystal structure of the 20S proteasome from the archaeon T. acidophilum at 3.4 A resolution., Lowe J, Stock D, Jap B, Zwickl P, Baumeister W, Huber R, Science. 1995 Apr 28;268(5210):533-9. PMID:7725097
Page seeded by OCA on Thu Feb 21 14:30:13 2008
