The present invention relates to methods, compositions, compounds and kits
for detecting, measuring and modulating protein ubiquitylation via the
N-end rule pathway and for identifying novel substrates, enzymes and
modulators of N-end rule ubiquitylation. The present invention also
relates to specific substrates of N-end rule ubiquitylation as well as
activated fragments of these substrates, proteases that expose N-degrons
in these substrates, ubiquitin ligases that ubiquitylate these substrates
and inhibitors of the ubiquitylation of these substrates.