Ulp2 is a SUMO-specific cysteine protease that removes SUMO from high-molecular-weight conjugates. It resides mainly in intranuclear foci, with a smaller cytoplasmic pool, and differs from the predominantly nuclear-pore-associated Ulp1 protease. Ulp2 has much weaker SUMO-precursor processing activity than Ulp1. It occurs in large complexes containing RNA-metabolism and translation proteins, including eIF4G, linking SUMO turnover to these cellular systems without establishing a specific translation-regulatory mechanism.
IPI PMID:24818994 The S. pombe translation initiation factor eIF4G is Sumoylat...
KEEP AS NON CORE
Summary: The interaction evidence establishes co-purification with translation and RNA-metabolism proteins, but generic protein binding does not specify Ulp2 molecular function.
Reason: The interaction evidence establishes co-purification with translation and RNA-metabolism proteins, but generic protein binding does not specify Ulp2 molecular function. Retain the physical-interaction evidence as non-core; SUMO deconjugation is the informative enzymatic activity.
HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ...
ACCEPT
Summary: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment.
Reason: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment. This also supports the conserved localization assertion without assuming that Ulp2 shares Ulp1 nuclear-pore localization.
Summary: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment.
Reason: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment. This also supports the conserved localization assertion without assuming that Ulp2 shares Ulp1 nuclear-pore localization.
Summary: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment.
Reason: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment. This also supports the conserved localization assertion without assuming that Ulp2 shares Ulp1 nuclear-pore localization.
Summary: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment.
Reason: Direct imaging shows predominantly nuclear Ulp2 foci and a smaller cytoplasmic pool, supporting this compartment. This also supports the conserved localization assertion without assuming that Ulp2 shares Ulp1 nuclear-pore localization.
Summary: The broad proteolysis/peptidase assertion is correct, but direct biochemical experiments establish SUMO deconjugation by a cysteine protease.
Reason: The broad proteolysis/peptidase assertion is correct, but direct biochemical experiments establish SUMO deconjugation by a cysteine protease. Use deSUMOylase activity to preserve modifier specificity; ubiquitin-like does not mean ubiquitin itself is the substrate.
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
Summary: The broad proteolysis/peptidase assertion is correct, but direct biochemical experiments establish SUMO deconjugation by a cysteine protease.
Reason: The broad proteolysis/peptidase assertion is correct, but direct biochemical experiments establish SUMO deconjugation by a cysteine protease. Use deSUMOylase activity to preserve modifier specificity; ubiquitin-like does not mean ubiquitin itself is the substrate.
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
IDA PMID:24818994 The S. pombe translation initiation factor eIF4G is Sumoylat...
UNDECIDED
Summary: The accessible full text shows stress-dependent eIF4G/SUMO cytoplasmic foci and separately localizes Ulp2, but does not unambiguously establish Ulp2 itself in stress granules.
Reason: The accessible full text shows stress-dependent eIF4G/SUMO cytoplasmic foci and separately localizes Ulp2, but does not unambiguously establish Ulp2 itself in stress granules. The source-specific localization requires inspection of the relevant target image or supplementary evidence. This does not contradict the independently demonstrated cytoplasmic Ulp2 pool.
Summary: Purified fission-yeast Ulp2 deconjugates SUMO from high-molecular-weight species in an NEM-sensitive assay, directly establishing the cysteine-protease mechanism and SUMO substrate specificity..
Reason: Purified fission-yeast Ulp2 deconjugates SUMO from high-molecular-weight species in an NEM-sensitive assay, directly establishing the cysteine-protease mechanism and SUMO substrate specificity.
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
IDA PMID:24818994 The S. pombe translation initiation factor eIF4G is Sumoylat...
ACCEPT
Summary: Purified fission-yeast Ulp2 deconjugates SUMO from high-molecular-weight species in an NEM-sensitive assay, directly establishing the cysteine-protease mechanism and SUMO substrate specificity..
Reason: Purified fission-yeast Ulp2 deconjugates SUMO from high-molecular-weight species in an NEM-sensitive assay, directly establishing the cysteine-protease mechanism and SUMO substrate specificity.
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
GO:0019783 ubiquitin-like protein peptidase activity
IEA GO_REF:0000117
MODIFY
Summary: The broad proteolysis/peptidase assertion is correct, but direct biochemical experiments establish SUMO deconjugation by a cysteine protease.
Reason: The broad proteolysis/peptidase assertion is correct, but direct biochemical experiments establish SUMO deconjugation by a cysteine protease. Use deSUMOylase activity to preserve modifier specificity; ubiquitin-like does not mean ubiquitin itself is the substrate.
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
Summary: The target can process SUMO precursor weakly in vitro, but the direct comparison shows substantially poorer maturation activity than Ulp1 and identifies deconjugation as its main role.
Reason: The target can process SUMO precursor weakly in vitro, but the direct comparison shows substantially poorer maturation activity than Ulp1 and identifies deconjugation as its main role. Retain the SUMO-specific endopeptidase assertion as a minor biochemical capacity rather than the core molecular function.
Using assays we described previously [13], we demonstrate that Ulp2 is significantly less able than Ulp1 to process SUMO to the mature form (Figure 1A, lane 2 (Ulp1) and lane 3 (Ulp2)), but is capable of deconjugating SUMO from high Mr species in an N-ethylmaleimide- (NEM)-dependent manner (Figure 1B).
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
EXP PMID:24818994 The S. pombe translation initiation factor eIF4G is Sumoylat...
UNDECIDED
Summary: Ulp2 co-purifies with translation factors and eIF4G sumoylation changes during osmotic stress.
Reason: Ulp2 co-purifies with translation factors and eIF4G sumoylation changes during osmotic stress. The paper does not establish an Ulp2-dependent change in translation rate or a resolved regulatory mechanism; its discussion explicitly leaves the role of eIF4G sumoylation open. The physiological translation-regulation assertion therefore remains unresolved.
These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins.
Q: Is eIF4G a direct physiological Ulp2 substrate, and does its deSUMOylation control translation initiation or stress-granule recruitment?
External Prediction Reviews
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
Review rationale: Purified fission-yeast Ulp2 directly deconjugates SUMO from high-molecular-weight species, and the study identifies it as a cysteine protease. SUMO is a ubiquitin-like modifier, so the broad ubiquitin-like protein peptidase term is biologically correct. The more specific deSUMOylase activity GO:0016929 is experimentally established and already annotated; the XML records hydration from that term. This prediction loses substrate specificity and is therefore LSP. It does not imply a demonstrated ability to remove ubiquitin itself.
Supporting Evidence:
PMID:24818994: "These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins."
Review rationale: Direct biochemical experiments establish Ulp2 as a SUMO-deconjugating cysteine protease, including sensitivity to N-ethylmaleimide. The conserved C48 catalytic domain is consistent with that mechanism. Cysteine-type peptidase activity is true but less precise than the already annotated deSUMOylase activity and its SUMO substrate specificity.
Supporting Evidence:
PMID:24818994: "These results confirm that like S. cerevisiae Ulp2, S. pombe Ulp2 is a cysteine protease whose main function is in deconjugating SUMO from target proteins."