Protein degradation occurs through several distinct proteolytic pathways for 
membrane and cytosolic proteins. There is evidence that these processes are 
linked and that crosstalk among these major protein degradation pathways occurs. 
Ubiquilins, a family of ubiquitin-binding proteins, are involved in all protein 
degradation pathways. This minireview provides an overview of ubiquilin function 
in protein degradation and contrasts it with sequestosome-1 (p62), a protein 
that also has been implicated in multiple proteolytic pathways.