T Cell Biology Class i molecules bind to peptides found in cytosol (e. g replicating viruses) Endogenous proteins are digested by natural processes Peptides from cytosol endoplasmic reticulum BIOL 533 Lecture 7BIOL 533 10 Lecture 7 T Cell Biology • Class I molecules bind to peptides found in cytosol (e.g., replicating viruses) • Endogenous proteins are digested by natural processes • Peptides from cytosol endoplasmic reticulum