Figure 3.

Involvement of UbK63 chains in selective autophagy.

UbK63 chains positively regulate the autophagic clearance of aggresomes, mitochondria and intracellular bacteria by interfering with various steps of the process. A. UbK63 chains on protein aggregates interact with distinct Ub-receptors to promote microtubule-dependent clustering at the MTOC (aggresome formation), autophagosome formation and fusion with the lysosome. DUBs played a role in two steps of the process. B. Mitochondria are marked by UbK63 chains to promote both perinuclear clustering and subsequent recruitment of the autophagic machinery. Targets and receptors of UbK63 chains on mitochondria remain ill-defined. C. Bacteria that escape the cytosol associated with remnant host membranes are rapidly decorated with UbK63 chains by host E3s to trigger autophagy via the simultaneous recruitment of multiple Ub-receptors.