Mass spectrometric characterization of the affinity-purified human 26S proteasome complex.

Article Details


Wang X, Chen CF, Baker PR, Chen PL, Kaiser P, Huang L

Mass spectrometric characterization of the affinity-purified human 26S proteasome complex.

Biochemistry. 2007 Mar 20;46(11):3553-65. Epub 2007 Feb 27.

PubMed ID
17323924 [ View in PubMed

The 26S proteasome is a multisubunit complex responsible for degradation of ubiquitinated substrates, which plays a critical role in regulating various biological processes. To fully understand the function and regulation of the proteasome complex, an important step is to elucidate its subunit composition and posttranslational modifications. Toward this goal, a new affinity purification strategy has been developed using a derivative of the HB tag for rapid isolation of the human 26S proteasome complex for subsequent proteomic analysis. The purification of the complex is achieved from stable 293 cell lines expressing a HB-tagged proteasome subunit and by high-affinity streptavidin binding with TEV cleavage elution. The complete composition of the 26S proteasome complex, including recently assigned new subunits, is identified by LC-MS/MS. In addition, all known proteasome activator proteins and components involved in the ubiquitin-proteasome degradation pathway are identified. Aside from the subunit composition, the N-terminal modification and phosphorylation of the proteasome subunits have been characterized. Twelve novel phosphorylation sites from eight subunits have been identified, and N-terminal modifications are determined for 25 subunits, 12 of which have not been previously reported in mammals. We also observe different N-terminal processing of subunit Rpn2, which results in identification of two different N-termini of the protein. This work presents the first comprehensive characterization of the human 26S proteasome complex by affinity purification and tandem mass spectrometry. The detailed proteomic profiling obtained here is significant to future studies aiming at a complete understanding of the structure-function relationship of the human 26S proteasome complex.

DrugBank Data that Cites this Article

NameUniProt ID
Proteasome subunit beta type-1P20618Details
Proteasome subunit beta type-5P28074Details
Proteasome subunit beta type-2P49721Details
Proteasome subunit alpha type-1P25786Details
Proteasome subunit alpha type-2P25787Details
Proteasome subunit alpha type-3P25788Details
Proteasome subunit alpha type-4P25789Details
Proteasome subunit alpha type-5P28066Details
Proteasome subunit alpha type-6P60900Details
Proteasome subunit alpha type-7O14818Details
Proteasome subunit beta type-3P49720Details
Proteasome subunit beta type-4P28070Details
Proteasome subunit beta type-6P28072Details
Proteasome subunit beta type-7Q99436Details
Proteasome activator complex subunit 1Q06323Details
26S protease regulatory subunit 6AP17980Details