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. Author manuscript; available in PMC: 2009 Feb 1.
Published in final edited form as: Curr Opin Struct Biol. 2008 Feb 13;18(1):43–51. doi: 10.1016/j.sbi.2007.12.014

Figure 2.

Figure 2

Pathways regulating the transfer of substrate to proteases in eukaryotes (a) and bacteria (b). Subunits of 26S proteasome bind to the polyubiquitin chain of modified substrate (2) or to exposed polypeptide sequence of the substrate (3). Alternatively, adaptor proteins that bind the polyubiquitin chain and the proteasome simultaneously can mediate targeting(1). Bacterial proteases recognize substrate via exposed sequence tags (3) or via adaptor proteins (4).