Specificity of the proteasome cleavage to the antigen protein

In the MHC class I molecule binding antigenic peptides processing and presentation pathway, the ubiquitin-proteasome system plays a key role in degrading the protein substrate. For the purpose of studying the specificities of proteasomal cleavage sites, partial least squares method is used to predict the proteasomal cleavage sites, and the predictive accuracy of the model is 82.8%. The specificities of the cleavage sites and the adjacent positions come from the contribution of the amino acids of the samples to the cleavage sites, showing the information of proteasome interacting with antigen protein. It demonstrates that the proteasome cleaving to target protein is selective, but not random.