Does anyone have insight as to whether the spectrum of peptides presented from a protein will be different whether the protein is expressed in the cell (e.g. gene delivery) via direct delivery of the protein? It is my understanding that expressed proteins can have a different spectrum of peptides presented as some will be from Defective Ribosome Initiation Products (DRIPs), while whole protein will primarily be degraded by the proteasome and endosomal/lysosomal proteases.
http://www.nature.com/nri/journal/v1/n2/fig_tab/nri1101-126a_F1.html
May be it helps
The proteasome degrades both defective protein products (DRIPS) of recent synthesis and proteins after the useful life. It,s been shown that DRIPS are the major source of peptides for tjhe classical MHCI antigen presentation pathway (proteasome and TAP dependent). Endocytic proteins undergo partial degradation into the vesicles and the resulting products can be directed for MHC I presentation, the so-called x-presentation. There are many mechanisms for x-presentation a tndhe presented peptides can indeed differ from those resulting when the protein is expressed within the cell.
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