Gid10 as an alternative N-recognin of the Pro/N-degron pathway

Significance In eukaryotes, N-degron pathways comprise proteolytic systems whose unifying feature is their ability to recognize proteins containing N-terminal degradation signals called N-degrons, thereby causing degradation of these proteins. Gid4, a subunit of the GID ubiquitin ligase in the yeastSaccharomyces cerevisiae , is the recognition component (N-recognin) of the Pro/N-degron pathway. Gid4 targets proteins by recognizing their N-terminal Pro residues or a Pro at position 2. We identified an uncharacterized Gid4-like yeast protein, termed Gid10. A screen for N-terminal sequence motifs that can bind to Gid10 showed that substrate specificities of Gid10 and Gid4 overlap but are not identical. We also found that Gid10 can function as a specific N-recognin of the GID ubiquitin ligase and the Pro/N-degron pathway.