title: Multicolor monitoring of the proteasome's catalytic signature.
abstract: The proteasome, a validated anticancer target, participates in an array of biochemical activities, which range from the proteolysis of defective proteins to antigen presentation. We report the preparation of biochemically and photophysically distinct green, red, and far-red real-time sensors designed to simultaneously monitor the proteasome's chymotrypsin-, trypsin-, and caspase-like activities, respectively. These sensors were employed to assess the effect of simultaneous multiple active site catalysis on the kinetic properties of the individual subunits. Furthermore, we have found that the catalytic signature of the proteasome varies depending on the source, cell type, and disease state. Trypsin-like activity is more pronounced in yeast than in mammals, whereas chymotrypsin-like activity is the only activity detectable in B-cells (unlike other mammalian cells). Furthermore, chymotrypsin-like activity is more prominent in transformed B cells relative to their counterparts from healthy donors.
authors.affiliation: Department of Chemistry, Division of Chemical Biology and Medicinal Chemistry, and Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States.
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Priestman
authors.forename: Qunzhao
authors.initials: Q
authors.lastname: Wang
authors.forename: Finith E
authors.initials: FE
authors.lastname: Jernigan
authors.forename: Ruma
authors.initials: R
authors.lastname: Chowdhury
authors.forename: Marion
authors.initials: M
authors.lastname: Schmidt
authors.forename: David S
authors.initials: DS
authors.lastname: Lawrence
mesh_terms: D000818:Animals; D002460:Cell Line; D005456:Fluorescent Dyes; D006801:Humans; D015394:Molecular Structure; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017510:Protein Folding; D011817:Rabbits; D012441:Saccharomyces cerevisiae; D054852:Small Molecule Libraries
chemical_list: D005456:Fluorescent Dyes; D054852:Small Molecule Libraries; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease