The proteasome is widely recognised as the central enzyme of non-lysosomal protein degradation. It is responsible for intracellular protein turnover and it is also critically involved in many regulatory processes and, in higher eukaryotes, in antigen processing.

• Gene/protein identifier: PSMB9 (gene name)
• Source: Purified from ascites
• Specificity: Recognises the β1i subunit of proteasome 20S

The 26S proteasome is the key enzyme of the ubiquitin/ATP-dependent pathway of protein degradation. The catalytic core of this unusually large (2000 kDa, 450 Å in length) complex is formed by the 20S proteasome, a barrel shaped structure shown by electron microscopy to comprise of four rings each containing seven subunits. Based on sequence similarity, all fourteen 20S proteasomal subunit sequences may be classified into two groups, α and β, each group having distinct structural and functional roles.

The α-subunits comprise the outer rings and the β-subunits the inner rings of the 20S proteasome. Observations of the eukaryotic proteasome and analysis of subunit sequences indicate that each ring contains seven different subunits (α7β7β7α7) with a member of each sub-family represented in each particle.

Each subunit is located in a unique position within the α- or β-rings. Lmp2, Lmp7 and MECL are interferon gamma-inducible catalytic subunits of the 20S proteasome which may replace the constitutive catalytic subunits, delta, X and Z respectively, during proteasome biogenesis. Lmp2 and Lmp7 alter the cleavage site specificity of the 20S proteasome and are required for the efficient generation of T cell epitopes from a number of viral proteins and for optimal MHC class I cell surface expression.

Application notes: The serum was characterised by single dimension SDS-PAGE using a HeLa cell lysate both with and without prior stimulation with γ-interferon. The mature LMP2 protein of ~22 kDa was detected by Western blotting in the γ-interferon stimulated cells and additionally the precursor form at ~25 kDa. Not suitable for immunoprecipitation.

Type:
Antigen: Proteasome subunit β type-9
Clonality: Monoclonal
Clone: LMP2-13
Conjugation:
Epitope:
Host: Mouse
Isotype: IgG1
Reactivity: Human, rat