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Selective Binding Of Airapl Tandem Uims To Lys48-Linked Tri-Ubiquitin Chains, Simin Rahighi, Ilauna Braunstein, Nicola Ternette, Benedikt Kessler, Masato Kawasaki, Ryuichi Kato, Tsutomu Matsui, Ariel Stanhill, Soichi Wakatsuki

Pharmacy Faculty Articles and Research

Lys48-linked ubiquitin chains act as the main targeting signals for protein degradation by the proteasome. Here we report selective binding of AIRAPL, a protein that associates with the proteasome upon exposure to arsenite, to Lys48-linked tri-ubiquitin chains. AIRAPL comprises two ubiquitin-interacting motifs in tandem (tUIMs) that are linked through a flexible inter-UIM region. In the complex crystal structure UIM1 binds the proximal ubiquitin, whereas UIM2 (the double-sided UIM) binds non-symmetrically to the middle and distal ubiquitin moieties on either side of the helix. Specificity of AIRAPL for Lys48-linked ubiquitin chains is determined by UIM2, and the flexible inter-UIM linker increases …