Figure 10.

Proposed Model for the Function of PUX10 on the LD.

LD proteins destined for degradation are marked with a polyubiquitin motif by K48-linked ubiquitins. This motif is recognized by the UBA domain of PUX10. PUX10 is an LD protein, attached to the organelle via its hydrophobic stretch (HS), and an amphipathic helix N-terminal of the HS. Via its UBX domain, PUX10 interacts with CDC48, recruiting this protein to the LD. CDC48 helps to channel the polyubiquitinated substrate to the proteasome. Whether CDC48 interacts directly with the proteasome, helps to extract the substrate from the LD, or recruits additional factors remains to be determined.