Introduction Session 1 and 2 (Ubiquitin, proteasome and human disease) WHAT S“ UBIQUITIN”? Main role: become a " label to target a substrate protein Protein Substrate Source: "Peptide models for protein beta-sheets PhD thesis, University of Nottingham, 2001 Figure by MIT OCW. Appendage of ubiquitin monomers to a fter Goodsell, D.S. The Oncologist 8, 293-294 protein substrate Ubiquitin is a small, 76 aa protein which gets appended to another proteins, as a label". The protein substrate has amino groups in the side chains of its Lys residues Ubiquitin has a C-terminal Gly G The carboxyl group of this Gly forms an isopeptide bond with the amino group of Hn the Lys in the protein substrate(see Inure Ubiquitin also has several lys that can Protein substrate act as internal acceptors for binding to the C-t Gly of new ubiquitin molecules, allowing the formation of a chainIntroduction Session 1 and 2 (Ubiquitin, proteasome and human disease) Appendage of ub prote Figure by MIT OCW. After Goodsell, D.S. The Oncologist 8, 293-294. Courtesy of Sam Griffiths-Jones. Used with permission. Source: "Peptide models for protein beta-sheets." PhD thesis, University of Nottingham, 2001. iquitin monomers to a in substrate. Ubiquitin is a small, 76 aa protein which gets appended to another proteins, as a “label”. The protein substrate has amino groups in the side chains of its Lys aa residues. Ubiquitin has a C-terminal Gly. The carboxyl group of this Gly forms an isopeptide bond with the amino group of the Lys in the protein substrate (see figure). Ubiquitin also has several Lys that can act as internal acceptors for binding to the C-t Gly of new ubiquitin molecules, allowing the formation of a chain