UFSP2 (UFM1-specific protease 2) is the principal human UFM1-specific cysteine (thiol-dependent) isopeptidase of the peptidase C78 family (catalytic Cys302). It acts in the UFM1 (ubiquitin-fold modifier 1) conjugation system, where it both processes pro-UFM1 to expose the activating C-terminal glycine and, predominantly, removes UFM1 from conjugated target proteins (deUFMylation). Documented substrates include the ribosomal protein RPL26/uL24, CYB5R3, DDRGK1, MRE11, TRIP4 and CD274/PD-L1. At the cytoplasmic surface of the endoplasmic reticulum, UFSP2 deUFMylates RPL26 on 60S ribosomal subunits, a step required to release the UFM1 E3 ligase complex and recycle 60S subunits after ribosome-associated quality control of stalled ER-translocating ribosomes. Through deUFMylation of CYB5R3 it modulates ER-phagy, and through TRIP4 it influences nuclear-receptor (estrogen receptor) transactivation. Loss-of-function and missense UFSP2 variants cause autosomal-dominant skeletal dysplasias (Beukes hip dysplasia, spondyloepimetaphyseal dysplasia) and a recessive neurodevelopmental/epileptic encephalopathy.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference that UFSP2 acts at the endoplasmic reticulum, where it deUFMylates RPL26 on ER-associated 60S ribosomes. Consistent with direct experimental evidence. Reason: UFSP2 is an ER-membrane-tethered deUFMylase; the IBA localization is corroborated by direct IDA evidence. Supporting Evidence: PMID:38383785 ER-membrane-tethered deUFMylase UFSP2 |
| GO:0071567 deUFMylase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of UFM1-specific protease (deUFMylase) activity, the core molecular function of UFSP2, directly supported by extensive biochemistry. Reason: deUFMylase activity is the central, repeatedly demonstrated function of UFSP2. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0005634 nucleus | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Phylogenetic inference of nuclear localization. Nuclear localization for human UFSP2 is supported only by sequence similarity to the mouse ortholog, not by direct human data; the dominant functional pool is at the ER/cytosol. Reason: Possible minor nuclear pool (e.g. TRIP4-related nuclear-receptor regulation) but not the core site of UFSP2's deUFMylase function; retained as non-core. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Nucleus {ECO:0000250|UniProtKB:Q99K23} |
| GO:0006508 proteolysis | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Generic proteolysis term reflecting the peptidase activity of UFSP2. The specific activity is UFM1-specific isopeptide/peptide cleavage, better captured by deUFMylase activity and protein maturation. Reason: Technically correct (UFSP2 is a protease) but uninformative compared with the specific deUFMylase activity; retained as non-core parent process. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0005634 nucleus | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Electronic localization to nucleus, inherited from the mouse ortholog; see the IBA/ISS nucleus annotations. Reason: Not the core site of action; supported only by orthology, retained as non-core. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Nucleus {ECO:0000250|UniProtKB:Q99K23} |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic localization to cytoplasm, consistent with the cytoplasmic/ER-surface site where UFSP2 acts on ribosomal and other substrates. Reason: Cytoplasm (including the cytoplasmic face of the ER) is a documented compartment for UFSP2 activity. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Cytoplasm {ECO:0000250|UniProtKB:Q99K23} |
| GO:0005783 endoplasmic reticulum | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic localization to ER, consistent with the experimentally established ER-membrane-tethered localization of UFSP2. Reason: ER is the principal functional site of UFSP2 (RPL26 deUFMylation); agrees with direct evidence. Supporting Evidence: PMID:38383785 ER-membrane-tethered deUFMylase UFSP2 |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | KEEP AS NON CORE | Summary: High-throughput binary interactome screen recording UFSP2 interactions with APOBEC1 and LMO1; the bare protein binding term is uninformative and these partners do not inform UFSP2's deUFMylase function. Reason: Records real interactions but the generic term is uninformative per curation guidelines; partners are not part of the core function. Supporting Evidence: file:human/UFSP2/UFSP2-goa.tsv GO:0005515 |
| GO:0032649 regulation of type II interferon production | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: Ortholog-based (Ensembl) electronic annotation transferring an interferon-gamma production phenotype from the mouse gene. No direct human evidence; not part of the characterized UFM1-protease function. Reason: Phenotype-based orthology transfer with no mechanistic link to UFSP2's deUFMylase activity in human; likely an indirect downstream consequence rather than a core function. Supporting Evidence: file:human/UFSP2/UFSP2-goa.tsv GO:0032649 |
| GO:0071567 deUFMylase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Automated electronic annotation of deUFMylase activity, redundant with and consistent with extensive experimental support. Reason: Correct core molecular function. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0005634 nucleus | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity-based nuclear localization transferred from the mouse ortholog (Q99K23). See the IBA/IEA nucleus annotations. Reason: Orthology-only support; not the core functional compartment. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Nucleus {ECO:0000250|UniProtKB:Q99K23} |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | ACCEPT | Summary: Sequence-similarity-based cytoplasmic localization, consistent with the cytoplasmic/ER-surface site of UFSP2 action. Reason: Cytoplasmic localization is well supported, including by direct human data. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Cytoplasm {ECO:0000250|UniProtKB:Q99K23} |
| GO:0071567 deUFMylase activity | IDA PMID:37795761 UFMylation of HRD1 regulates endoplasmic reticulum homeostas... | ACCEPT | Summary: Direct evidence for UFSP2 deUFMylase activity in the context of HRD1 UFMylation and ER homeostasis. Reason: Direct experimental support for the core deUFMylase activity. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0071567 deUFMylase activity | IDA PMID:36893266 Dysregulation of PD-L1 by UFMylation imparts tumor immune ev... | ACCEPT | Summary: Direct evidence for UFSP2 deUFMylase activity. Reason: Direct experimental support for the core deUFMylase activity. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0042177 negative regulation of protein catabolic process | IDA PMID:36543799 The UFM1 system regulates ER-phagy through the ufmylation of... | KEEP AS NON CORE | Summary: UFSP2 deUFMylates CYB5R3; because CYB5R3 UFMylation signals ER-phagy (degradation), UFSP2 activity opposes this catabolic route. The negative regulation of a degradation process is a downstream consequence of its deUFMylase activity. Reason: Plausible process outcome of UFSP2 reversing CYB5R3 UFMylation, but a downstream/context-specific effect rather than the core molecular function. Supporting Evidence: PMID:36543799 overexpression of UFSP2 but not the active-site mutant UFSP2C302A decreased the amount of the UFM1~CYB5R3 conjugate |
| GO:0071567 deUFMylase activity | IDA PMID:31595041 UFMylation of RPL26 links translocation-associated quality c... | ACCEPT | Summary: Direct evidence for UFSP2 deUFMylase activity on a target substrate. Reason: Direct experimental support for the core deUFMylase activity. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0071567 deUFMylase activity | IDA PMID:36543799 The UFM1 system regulates ER-phagy through the ufmylation of... | ACCEPT | Summary: Direct demonstration that wild-type UFSP2, but not the catalytic Cys302Ala mutant, removes UFM1 from CYB5R3, establishing UFSP2 deUFMylase activity on this ER substrate. Reason: Active-site-dependent removal of UFM1 from a defined substrate; strong direct support for the core function. Supporting Evidence: PMID:36543799 overexpression of UFSP2 but not the active-site mutant UFSP2C302A decreased the amount of the UFM1~CYB5R3 conjugate |
| GO:0072344 rescue of stalled cytosolic ribosome | IDA PMID:38383785 UFM1 E3 ligase promotes recycling of 60S ribosomal subunits ... | ACCEPT | Summary: UFSP2 deUFMylation of RPL26/uL24 is required to release the UFM1 E3 ligase from UFMylated 60S subunits, enabling 60S recycling after RQC-mediated splitting of ribosomes stalled during co-translational ER translocation. Reason: Directly supported role in the ribosome-rescue/recycling arm of ER-associated RQC; this is a key biological process for UFSP2. Supporting Evidence: PMID:38383785 UFMylation facilitates the rescue of 60S ribosomal subunits (60S) that are released after ribosome-associated quality-control-mediated splitting of ribosomes that stall during co-translational translocation of secretory proteins into the ER |
| GO:0005783 endoplasmic reticulum | IDA PMID:35926457 Human UFSP1 is an active protease that regulates UFM1 matura... | ACCEPT | Summary: Direct evidence that UFSP2 acts at the ER (in contrast to cytosolic UFSP1), where it removes UFM1 from the ribosomal subunit RPL26. Reason: Establishes the ER as the functional compartment for UFSP2's RPL26 deUFMylation. Supporting Evidence: PMID:35926457 While UFSP2, but not UFSP1, removes UFM1 from the ribosomal subunit RPL26 |
| GO:0032790 ribosome disassembly | IDA PMID:38383785 UFM1 E3 ligase promotes recycling of 60S ribosomal subunits ... | ACCEPT | Summary: UFSP2-mediated deUFMylation of RPL26 releases the UFM1 E3 ligase clamp from the 60S subunit, contributing to disassembly/recycling of post-RQC 60S ribosomal subunits. Reason: Directly supported role in releasing the E3-UFM1 clamp to allow 60S recycling. Supporting Evidence: PMID:38383785 UFM1 E3 ligase promotes recycling of 60S ribosomal subunits from the ER |
| GO:0071567 deUFMylase activity | IMP PMID:27926783 A novel approach to assess the ubiquitin-fold modifier 1-sys... | ACCEPT | Summary: Mutational/phenotypic evidence supporting UFSP2 as the active deUFMylase mediating deconjugation of UFM1 from target proteins. Reason: Supports the core deUFMylase activity; UFSP2 mainly acts as a protein deUFMylase. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt UFSP2 mainly acts as a protein deUFMylase that mediates deconjugation of UFM1 from target proteins |
| GO:0071567 deUFMylase activity | IDA PMID:35926457 Human UFSP1 is an active protease that regulates UFM1 matura... | ACCEPT | Summary: Direct evidence that UFSP2 removes UFM1 from RPL26, confirming deUFMylase activity. Reason: Direct experimental support for the core deUFMylase activity. Supporting Evidence: PMID:35926457 While UFSP2, but not UFSP1, removes UFM1 from the ribosomal subunit RPL26 |
| GO:0071567 deUFMylase activity | IDA PMID:38383785 UFM1 E3 ligase promotes recycling of 60S ribosomal subunits ... | ACCEPT | Summary: UFSP2 deUFMylates RPL26 on 60S subunits, the activity underlying 60S recycling. Reason: Direct support for the core deUFMylase activity in the ribosome-recycling context. Supporting Evidence: PMID:38383785 ER-membrane-tethered deUFMylase UFSP2 |
| GO:0071567 deUFMylase activity | IMP PMID:33473208 A pathogenic UFSP2 variant in an autosomal recessive form of... | ACCEPT | Summary: A pathogenic UFSP2 variant impairs UFMylation homeostasis, consistent with UFSP2 functioning as the active UFM1-specific peptidase; mutant phenotype supports the enzymatic role. Reason: Disease-variant evidence supports UFSP2's deUFMylase/UFM1-protease function. Supporting Evidence: PMID:33473208 UFM1-specific peptidase 2 (UFSP2), which participates in the UFMylation pathway |
| GO:0071567 deUFMylase activity | IMP PMID:32160526 A Genome-wide ER-phagy Screen Highlights Key Roles of Mitoch... | ACCEPT | Summary: Mutational evidence supporting UFSP2 deUFMylase activity. Reason: Supports the core deUFMylase activity. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0033146 regulation of intracellular estrogen receptor signaling pathway | IMP PMID:25219498 Modification of ASC1 by UFM1 is crucial for ERΞ± transactivat... | KEEP AS NON CORE | Summary: UFSP2 deUFMylates the coactivator TRIP4/ASC-1, regulating nuclear-receptor (including estrogen receptor) transactivation. A context-specific downstream role of UFSP2's deUFMylase activity. Reason: A genuine but context-specific regulatory process downstream of UFSP2 deUFMylating TRIP4; not the core molecular function. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Catalyzes deUFMylation of TRIP4, regulating intracellular nuclear receptors transactivation |
| GO:0006508 proteolysis | IMP PMID:25219498 Modification of ASC1 by UFM1 is crucial for ERΞ± transactivat... | KEEP AS NON CORE | Summary: Generic proteolysis term reflecting UFSP2's peptidase activity (here in the TRIP4 deUFMylation study). The specific activity is UFM1-specific cleavage. Reason: Correct but uninformative parent term relative to deUFMylase activity. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Thiol-dependent isopeptidase that specifically cleaves UFM1 |
| GO:0071567 deUFMylase activity | IMP PMID:25219498 Modification of ASC1 by UFM1 is crucial for ERΞ± transactivat... | ACCEPT | Summary: UFSP2 deUFMylates TRIP4; mutational/functional evidence supports the deUFMylase activity on this substrate. Reason: Supports the core deUFMylase activity with a defined substrate (TRIP4). Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Catalyzes deUFMylation of TRIP4, regulating intracellular nuclear receptors transactivation |
| GO:0005515 protein binding | IPI PMID:25219498 Modification of ASC1 by UFM1 is crucial for ERΞ± transactivat... | KEEP AS NON CORE | Summary: Records a UFSP2-TRIP4 (Q15650) interaction (the substrate it deUFMylates). The bare protein binding term is uninformative; the functionally meaningful relationship is enzyme-substrate. Reason: Reflects the UFSP2-TRIP4 substrate interaction but the generic term is uninformative per curation guidelines. Supporting Evidence: file:human/UFSP2/UFSP2-uniprot.txt Catalyzes deUFMylation of TRIP4, regulating intracellular nuclear receptors transactivation |
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Download this section (compressed HTML)Q: How is the choice between UFSP2 pro-UFM1 maturation and substrate deUFMylation regulated, and what determines its substrate selectivity (RPL26 vs CYB5R3 vs TRIP4)?
Q: How do the skeletal-dysplasia missense variants versus the recessive neurodevelopmental variant differ mechanistically in their effect on UFSP2 catalysis and the resulting UFMylation balance?
Experiment: Substrate-resolved UFM1-conjugate proteomics in UFSP2-knockout versus catalytically dead (C302A) rescue cells to map the in vivo deUFMylation substrate repertoire.
Experiment: Reconstitute UFMylated 60S recycling in vitro with purified UFSP2 to test whether RPL26 deUFMylation is necessary and sufficient to release the UFM1 E3 ligase clamp.
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