ユビキチン鎖の認識と選択的切断メカニズムの構造的理解

抄録

Ubiquitin is a conserved 76-residue protein that is reversibly conjugated with substrate proteins to regulate various cellular processes. The terminal carboxyl group of ubiquitin can be bonded to lysine residues of substrate proteins including ubiquitin itself. All seven lysine residues (K6, K11, K27, K29, K33, K48 and K63) and the N-terminal Met can act as receptors for the conjugation, producing polyubiquitin chains. For instance, the most abundant K48-linked chains serve as signals for proteasomal degradation, whereas K63-linked chains function in other proteasome-independent processes. Here we show how these functionally and structurally distinct chains are discriminated by linkage-specific deubiquitinating enzymes and binding proteins.