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Poly‐ubiquitin Chains Paradox: Development of Novel and Selective Poly‐ubiquitin Binding Domains
Author(s) -
Mason Mark,
Bellam Julia,
Strickler James
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.883.14
Subject(s) - ubiquitin , microbiology and biotechnology , chemistry , biochemistry , biology , computational biology , gene
Ubiquitylation occurs through linkage between the C‐terminus of Ub and the ε‐amino group of a Lys on the target substrate. Ub has 7 Lys residues (K6, K11, K27, K29, K33, K48, and K63), each of which can participate in generating poly‐Ub chains. The ability of Ub to form polymers is central to the versatility of this system in regulating cellular processes. The most extensively characterized of these polymers are linked through either K48 or K63. K48‐linked polyUb predominantly targets proteins for proteasomal degradation, whereas K63‐linked polyUb appears to regulate protein function, localization, or interactions. K11‐linked polyUb has been implicated in mitotic regulation and ERAD. It is apparent that different poly‐ubiquitin linkages convey different information to the cell and strongly suggests that the cell contains elements capable of decoding this information, i.e. linkage specific ubiquitin binding domains. Development of Poly‐Ubiquitin selective tools will revolutionize the field of ubiquitin. Most UBDs described to date show little ability to discriminate between different linkages; although, it is possible to construct linkage specific tandem ubiquitin binding entities (TUBEs) by manipulating the spacing and rigidity of the linkers between tandem UBDs. We and our collaborators have constructed a series of K63‐specific UBDs that are useful for Far Western blotting and “pull‐down” type experiments for evaluating the levels and identities of proteins bearing K63‐linked polyubiquitin chains. We report here on the development of new TUBE‐type reagents that distinquish between chain linkages and can be used in dissecting the exact role of the different linkages in ubiquitin biology. This information will impact on our understanding of the UPP and suggest new targets for intervention.