The following examples highlight the functionality of IUPred2A in the identification of
various forms of protein disorder.
All figures are reproducible using IUPred2A by simply entering the given UniProt ID and
selecting the corresponding options.
Human p53 (UniProt ID: P04637)
p53 is a tumor suppressor protein involved in apoptosis, cell cycle control and
transcription regulation. It
consists of the disordered N-terminal and C-terminal parts and the central largely ordered
DNA binding domain.
The N- and C-terminal parts contain the trans-activation and the tetramerization motifs,
respectively, each with
its own Pfam motif. The structure of the central DNA binding domain (DBD) was determined
both in isolation and bound to
DNA as well. However, the disordered regions also incorporate a large number of solved
structures from the PDB, but
since these regions do not have a stable structure on their own, their structures can only
be determined when bound
to some molecular partner.
The disorder prediction score in red correctly highlights the ordered nature of the DBD and
the disordered nature of both
termini. Both the N- and the C-terminal binding motifs display reduced disorder tendency,
which is a characteristic feature
of protein-interacting disordered binding sites.
Cytochrome c oxidase copper chaperone (UniProt ID: Q14061)
COX17 is a critically important subunit of the human cytochrome c oxidase. COX17 is a
cystein-rich protein, and the redox
state of these cysteine residues (and hence their role in protein stability) is highly
dependent on the sub-cellular localization
of the protein. Upon entring the oxidative environment of the mitochondrium, COX17 undergoes
a disorder-to-order transition,
forming a stable coiled-coil/helix/coiled-coil/helix structure (see Banci et
The redox state-dependent conditional disorder of COX17 can be correctly predicted with the
new, redox state-dependent prediction
of IUPred2A. IUPred2A correctly shows the redox sensitive region.
E. coli 33 kDa chaperonin (Hsp33) (UniProt ID: P0A6Y5)
Hsp33 belongs to the holdase class of molecular chaperones. The activity of Hsp33 depends on
oxidative conditions, however, for this protein the functional state is disordered. Under
non-stress conditions, Hsp33 is a compactly folded zinc-binding protein with negligible
activity. Oxidative stress causes the formation of two intramolecular disulfide bonds and
the release of Zn2+ ions. This leads to the unfolding of the zinc-binding domain, exposing
the substrate binding surface of the chaperone that is necessary for its activity.
The redox switch domain between residues 224-285 is correctly highlighted by the
redox-dependent disorder prediction of IUPred2A.
Early E1A protein (UniProt ID: P03255)
Human adenovirus C early E1A protein is a largely disordered protein essential for forcing
host cell into S phase via modulation of the Rb1/E2F1 pathway and the inhibition of
modulation of p53 degradation. These host-pathogen interactions are mediated by several
Rb1 and CBP are targeted by two N-terminal tandem binding sites with determined complex
deposited in the PDB, shown in green and red boxes. These known disordered binding regions
identified by ANCHOR2 as two distinct neighbouring peaks in the output score. While no other
human protein complexes are currently known in structural detail, E1A harbors two additional
motifs between residues 113-126 capable of forming host-specific interactions. Both motifs,
the putative binding site for the deubiquitinase UBE2I between residues 76-140 are correctly
by ANCHOR2 as a separate peak in the prediction score. A distinct peak C-terminal around
has no known binding partners; however it entails a serine residue that was shown
to be heavily
phosphorylated by host kinases, hinting at an
additional important binding region with currently limited characterization.
p27/Cyclin-dependent kinase inhibitor 1B (UniProt ID: P46527)
p27 is one of the major regulators of cell cycle progression, being an inhibitor of the
CDK2/cyclinA complex. p27 is fully disordered and
binds to the target complex using a large extended interface harboring several strongly
binding regions interspersed with weak binding linkers.
The graph shows the region of p27 that becomes ordered during the interaction. ANCHOR not
only predicts correctly the binding event, but it
is also able to pinpoint the strongly binding regions with the provided ANCHOR score having
a strong correclation with the number of intermolecular
atomic contacts (see Meszaros et
Hemoglobin subunit alpha (UniProt ID: P69905)
Hemoglobin subunits are globular proteins, lacking disordered regions and thus lacking
binding regions as well. The figure shows that both the IUPred2 prediction (red line) and
predictions (blue line) are consistent with this fact, predicting no disorder or disordered
binding regions in