Which of the following is the main criterion that determines whether a protein is processed and presented via the class I MHC pathway in an antigen-presenting cell (APC)?
A)Encoded by a viral gene
B)Present in an acidic vesicular compartment of the APC
C)Present in the cytosol of the APC
D)Internalized into the cell from the extracellular space
E)Small in size

Question

Quizplus · Accepted Answer

Regardless of the source of the protein,its presence in the cytosol makes it accessible to the tagging and proteolytic processing mechanisms that initiate the class I MHC antigen presentation pathway.Microbial proteins and self proteins have equal access to this pathway if they are present in the cytosol.Presence in acidic vesicles is the comparable major criterion for inclusion in the class II MHC pathway;such proteins are usually,but not always,internalized from the extracellular space.The size of an intact protein is not relevant to which processing and presentation pathway it will enter.

Which of the Following Is the Main Criterion That Determines