However, most secreted proteins were detected as homo- or heteroligomers. SB202190 cost Two typical examples were the TCP-1 complex and the aminopeptidase M17. The TCP-1 complex is a chaperone complex of eight distinct subunit species (α, β, γ, δ, ε, η, θ and ζ)We identified the TCP-1 complex in spots 44 and 45 corresponding to a native mass between 400 and 450 kDa (expected size: 440 kDa). Aminopeptidase M17 (50 kDa) has been reported to form a homohexameric structure [15],

and we found this enzyme (spot 165) with a native mass of approximately 250 kDa. Figure 4 BN-PAGE separation of the T. brucei gambiense secretome (OK strain). Proteins were separated by native gel electrophoresis (BN-PAGE) and stained with coomassie brilliant blue. Coomassie-stained protein spots (186) were excised, digested with find more trypsin, and identified by MS/MS. 382 proteins were identified and the associated data (accession numbers, molecular masses and MS/MS data) are presented in additional file 2, Table S2. ABT-737 nmr Another striking feature concerned the proteasome, which we identified in two

forms (spots 48-55 and 56-65) in the secretome. The 20S proteasome is a 28-mer composed of two stacked heptameric rings of proteolytically active beta subunits, surmounted at each end by another heptameric ring of structural alpha subunits. Seven alpha and seven beta paralogs exist in the T. brucei genome and all of the 14 different subunits were identified in both lanes, except alpha3 in the highest MW complex. The 20S core is regulated by additional 19S or 11S complexes. In T. brucei, a form of the 20S proteasome showing enhanced peptidase activity was previously described, and a 26-kDa protein, PA26 (26-kDa proteasome activator protein), was proposed to correspond to the 11S activator known in mammals [16, 17]. We identified PA26 in both complexes. Because of the sizes of the two proteasome complexes (300-350 kDa) and the average size of the alpha and

beta subunits (~25 kDa), the two forms of the proteasome complex identified here probably contain a single ring of alpha and beta subunits. Moreover, from the size of the highest MW complex and the apparent stoichiometry between PA26 and the other subunits in the complex, 3-oxoacyl-(acyl-carrier-protein) reductase the highest MW complex may represent the activated form of the complex. Finally, it should be pointed out that the 19S and 20S subunits were also identified in the unresolved part of the gel (spots 1-18), corresponding to complexes above 1000 kDa, and they could reveal a minor form of the 26S proteasome that has not been identified in T. brucei to date. 3- Secreted proteins correspond to a specific subset of the trypanosome proteome A few proteomic data sets were recently published for members of the Trypanosomatidae family, including the total proteome of T.