Rat Dusp21 encodes a small (189 aa) atypical dual specificity protein phosphatase of the DUSP18/DUSP21 subfamily, with a single DSPc catalytic domain containing the CX5R P-loop and a catalytic cysteine (Cys105) but no MAPK-docking or CH2 domain. It is expressed essentially only in testis. The orthologous enzyme hydrolyses phosphotyrosine and, less efficiently, phosphothreonine substrates in vitro. In rat testis the endogenous protein is imported into mitochondria through an internal targeting sequence and is a peripheral protein of the inner membrane on its matrix face. In mouse spermatozoa the ortholog is a microtubule inner protein anchored to tektin filaments in the A-tubule lumen of the flagellar doublet microtubules; its loss raises phosphorylation of axonemal proteins but leaves sperm motility and fertility normal. Physiological substrates are unknown.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004721 phosphoprotein phosphatase activity | IEA GO_REF:0000107 | MODIFY | Summary: Phosphoprotein phosphatase activity transferred from mouse Dusp21 via Ensembl Compara. True, but the enzyme is a dual-specificity (pTyr and pSer/pThr) phosphatase, for which GO:0008138 is the specific child term. Reason: Correct but general. DUSP21 is an atypical dual-specificity phosphatase with a CX5R P-loop and catalytic Cys; recombinant murine DSP21 is active and the C-to-S mutant is dead, and the human protein dephosphorylates both pTyr and pThr peptides. GO:0008138 protein tyrosine/serine/threonine phosphatase activity is_a GO:0004721 (checked with OAK) and is already carried by this gene (InterPro-based IEA row). Proposed replacements: protein tyrosine/serine/threonine phosphatase activity Supporting Evidence: PMID:18385140 Mutation of the catalytic active site cysteine to serine abolished phosphatase activity of both DSP18 and DSP21 PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" |
| GO:0004721 phosphoprotein phosphatase activity | ISO GO_REF:0000121 | MODIFY | Summary: Phosphoprotein phosphatase activity by ISO from mouse Dusp21 (MGI:1920797, whose IDA rests on PMID:37295417). True, but less specific than the supported dual-specificity term. Reason: Correct but general. DUSP21 is an atypical dual-specificity phosphatase with a CX5R P-loop and catalytic Cys; recombinant murine DSP21 is active and the C-to-S mutant is dead, and the human protein dephosphorylates both pTyr and pThr peptides. GO:0008138 protein tyrosine/serine/threonine phosphatase activity is_a GO:0004721 (checked with OAK) and is already carried by this gene (InterPro-based IEA row). Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: MGI:MGI:1920797 · MGI:MGI:1920797 SUPPORTS TRANSFER Mouse ortholog has direct evidence of phosphatase activity; the transfer to rat is sound, only the granularity is improved by GO:0008138. Proposed replacements: protein tyrosine/serine/threonine phosphatase activity Supporting Evidence: PMID:18385140 Mutation of the catalytic active site cysteine to serine abolished phosphatase activity of both DSP18 and DSP21 PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" |
| GO:0004722 protein serine/threonine phosphatase activity | IEA GO_REF:0000003 | KEEP AS NON CORE | Summary: Protein serine/threonine phosphatase activity from the EC 3.1.3.16 mapping (ARBA-derived catalytic activity lines in the TrEMBL record). Reason: Atypical DUSPs dephosphorylate phosphothreonine as well as phosphotyrosine in vitro, and human DUSP21 dephosphorylated monophosphorylated pThr MAPK peptides, though with clear preference for pTyr. The Ser/Thr half of the activity is real but secondary; the core function is captured by GO:0008138 (which is not a descendant of GO:0004722, so MODIFY is not a refinement here). Supporting Evidence: PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. |
| GO:0004722 protein serine/threonine phosphatase activity | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: Protein serine/threonine phosphatase activity by ISO from mouse Dusp21. Reason: Atypical DUSPs dephosphorylate phosphothreonine as well as phosphotyrosine in vitro, and human DUSP21 dephosphorylated monophosphorylated pThr MAPK peptides, though with clear preference for pTyr. The Ser/Thr half of the activity is real but secondary; the core function is captured by GO:0008138 (which is not a descendant of GO:0004722, so MODIFY is not a refinement here). Supporting Evidence: PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. |
| GO:0004725 protein tyrosine phosphatase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Protein tyrosine phosphatase activity inferred by PAINT at node PTN002925657 (DUSP18/DUSP21 clade), seeded by mouse and human DUSP18 and DUSP21. Reason: Rat Dusp21 sits inside the DUSP18/21 clade, retains the catalytic Cys (FT ACT_SITE 105) and the DSPc domain, and the clade members prefer phosphotyrosine substrates (pNPP, pTyr peptides). No evidence of loss of activity. Tyrosine dephosphorylation is the preferred activity of this dual-specificity enzyme. Supporting Evidence: PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. PMID:18385140 These results demonstrate that DSP18 and DSP21 are catalytically active phosphatases having kinetic constants consistent with other members of the DSP family of phosphatases. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" |
| GO:0004725 protein tyrosine phosphatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Protein tyrosine phosphatase activity by combined automated annotation (EC 3.1.3.48 / Rhea from PROSITE-ProRule PRU10044). Reason: Supported by the conserved PTP active-site signature and by direct activity of the orthologs on pTyr substrates. Supporting Evidence: PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. PMID:18385140 These results demonstrate that DSP18 and DSP21 are catalytically active phosphatases having kinetic constants consistent with other members of the DSP family of phosphatases. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" |
| GO:0004725 protein tyrosine phosphatase activity | ISO GO_REF:0000121 | ACCEPT | Summary: Protein tyrosine phosphatase activity by ISO from MGI:MGI:1920797. Reason: Ortholog has direct evidence for tyrosine phosphatase activity (pNPP and pTyr peptides); rat Dusp21 retains the catalytic Cys and P-loop. Supporting Evidence: PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. PMID:18385140 These results demonstrate that DSP18 and DSP21 are catalytically active phosphatases having kinetic constants consistent with other members of the DSP family of phosphatases. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" |
| GO:0004725 protein tyrosine phosphatase activity | ISO GO_REF:0000121 | ACCEPT | Summary: Protein tyrosine phosphatase activity by ISO from UniProtKB:Q9H596. Reason: Ortholog has direct evidence for tyrosine phosphatase activity (pNPP and pTyr peptides); rat Dusp21 retains the catalytic Cys and P-loop. Supporting Evidence: PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. PMID:18385140 These results demonstrate that DSP18 and DSP21 are catalytically active phosphatases having kinetic constants consistent with other members of the DSP family of phosphatases. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" |
| GO:0005634 nucleus | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: Nucleus, transferred from the human ortholog (UniProt SubCell SL-0191). Reason: The nuclear/cytoplasmic localization of DUSP21 comes from N-terminally tagged overexpression in COS cells (Hood et al. 2002). Endogenous DSP21 in rat testis is mitochondrial, and N-terminal tags were shown to block mitochondrial import of DSP18/21; mouse sperm structural work places it in the axoneme. There is no endogenous evidence for a nuclear pool. Supporting Evidence: PMID:18385140 However, these were overexpression experiments utilizing N-terminal tags which have been shown to commonly disrupt the localization of mitochondrial proteins PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment |
| GO:0005634 nucleus | ISO GO_REF:0000121 | MARK AS OVER ANNOTATED | Summary: Nucleus by ISO from human DUSP21 (Q9H596). Reason: The nuclear/cytoplasmic localization of DUSP21 comes from N-terminally tagged overexpression in COS cells (Hood et al. 2002). Endogenous DSP21 in rat testis is mitochondrial, and N-terminal tags were shown to block mitochondrial import of DSP18/21; mouse sperm structural work places it in the axoneme. There is no endogenous evidence for a nuclear pool. Propagation Review Root cause: SOURCE WEAK OR INFERRED Failure modes: SOURCE EVIDENCE WEAK COMPARTMENT OR COMPLEX MISMATCH Sources checked: UniProtKB:Q9H596 · UniProtKB:Q9H596 SOURCE WEAK OR INFERRED The human nuclear annotation rests on N-terminally tagged overexpression, which mislocalizes this mitochondrially targeted phosphatase. Supporting Evidence: PMID:18385140 However, these were overexpression experiments utilizing N-terminal tags which have been shown to commonly disrupt the localization of mitochondrial proteins PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment |
| GO:0005730 nucleolus | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: Nucleolus, transferred from the human ortholog via Ensembl Compara. Reason: No study of endogenous rodent DUSP21 reports nucleolar localization; endogenous protein is mitochondrial (rat testis) or axonemal (mouse sperm). The human source annotation could not be inspected and is not corroborated for the rodent protein. Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT |
| GO:0005730 nucleolus | ISO GO_REF:0000121 | MARK AS OVER ANNOTATED | Summary: Nucleolus by ISO from human DUSP21 (Q9H596). Reason: No study of endogenous rodent DUSP21 reports nucleolar localization; endogenous protein is mitochondrial (rat testis) or axonemal (mouse sperm). The human source annotation could not be inspected and is not corroborated for the rodent protein. Propagation Review Root cause: SOURCE WEAK OR INFERRED Failure modes: SOURCE EVIDENCE WEAK COMPARTMENT OR COMPLEX MISMATCH Sources checked: UniProtKB:Q9H596 · UniProtKB:Q9H596 SOURCE WEAK OR INFERRED Human source annotation is not corroborated by any endogenous localization of rodent DUSP21, which is mitochondrial or axonemal. Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | MODIFY | Summary: Cytoplasm (is_active_in) inferred by PAINT at PTN002925657 for the DUSP18/21 clade. Reason: True but general: both supported locations of endogenous DUSP21, the mitochondrial matrix (rat testis) and the A-tubule lumen of the sperm axoneme (mouse), are part_of cytoplasm (checked with OAK). The informative locations are GO:0005759 and GO:0160111, both already carried by this gene. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN002925657 · PANTHER:PTN002925657 SUPPORTS TRANSFER The clade-level cytoplasm claim holds (mitochondrial and axonemal compartments are cytoplasmic), but the node stops at a coarse term because DUSP18 (intermembrane space) and DUSP21 (matrix, axoneme) differ in sub-compartment. Proposed replacements: mitochondrial matrix axonemal A tubule inner sheath Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | MODIFY | Summary: Cytoplasm from the human ortholog SubCell annotation (SL-0086). Reason: True but general: both supported locations of endogenous DUSP21, the mitochondrial matrix (rat testis) and the A-tubule lumen of the sperm axoneme (mouse), are part_of cytoplasm (checked with OAK). The informative locations are GO:0005759 and GO:0160111, both already carried by this gene. Proposed replacements: mitochondrial matrix axonemal A tubule inner sheath Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT |
| GO:0005737 cytoplasm | ISO GO_REF:0000121 | MODIFY | Summary: Cytoplasm by ISO from human DUSP21. Reason: True but general: both supported locations of endogenous DUSP21, the mitochondrial matrix (rat testis) and the A-tubule lumen of the sperm axoneme (mouse), are part_of cytoplasm (checked with OAK). The informative locations are GO:0005759 and GO:0160111, both already carried by this gene. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: UniProtKB:Q9H596 · UniProtKB:Q9H596 SUPPORTS TRANSFER Cytoplasm is true but general; human source rests on tagged overexpression, but the claim holds at this level for the rodent protein. Proposed replacements: mitochondrial matrix axonemal A tubule inner sheath Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT |
| GO:0005743 mitochondrial inner membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Mitochondrion inner membrane from UniProt SubCell mapping (SL-0168). Reason: Rat testis subfractionation places DSP21 in inner-membrane fractions (SMP and mitoplasts), protected in mitoplasts and released by alkaline but not salt wash, i.e. a peripheral inner-membrane protein on the matrix face. Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment PMID:18385140 This indicates that DSP21, like DSP18, is a peripheral membrane protein |
| GO:0005759 mitochondrial matrix | IDA PMID:18385140 Dual specificity phosphatases 18 and 21 target to opposing s... | ACCEPT | Summary: Mitochondrial matrix, IDA from rat testis mitochondrial subfractionation (Rardin et al. 2008). Reason: Full text read. Gradient-purified rat testis mitochondria (ER marker calreticulin removed); DSP21 enriched in mitoplast and SMP fractions, trypsin-protected in mitoplasts but digested in inverted SMPs, and removed by alkaline wash: a peripheral inner-membrane protein facing the matrix. Matrix-side localization is the best-supported location for the endogenous rat protein. Supporting Evidence: PMID:18385140 collectively these data suggest that DSP21 is localized to mitochondria in testis tissue where it peripherally associates with the IM within the matrix compartment |
| GO:0008138 protein tyrosine/serine/threonine phosphatase activity | IEA GO_REF:0000104 | ACCEPT | Summary: Protein tyrosine/serine/threonine phosphatase activity transferred by UniRule UR000414439. Reason: Core molecular function. DUSP21 is an atypical dual-specificity phosphatase: conserved catalytic Cys in the DSPc domain, activity of recombinant murine DSP21 abolished by C-to-S mutation, and in vitro dephosphorylation of both pTyr and pThr peptides by the human protein. Supporting Evidence: PMID:18385140 Mutation of the catalytic active site cysteine to serine abolished phosphatase activity of both DSP18 and DSP21 PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. file:rat/Dusp21/Dusp21-uniprot.txt /note="Phosphocysteine intermediate" file:rat/Dusp21/Dusp21-uniprot.txt Pfam; PF00782; DSPc; 1. |
| GO:0016787 hydrolase activity | IEA GO_REF:0000104 | MODIFY | Summary: Hydrolase activity from UniRule UR000414439. Reason: Correct but uninformative; GO:0008138 protein tyrosine/serine/threonine phosphatase activity (a descendant, already carried by the gene) is the supported specific activity. Proposed replacements: protein tyrosine/serine/threonine phosphatase activity Supporting Evidence: PMID:18385140 Mutation of the catalytic active site cysteine to serine abolished phosphatase activity of both DSP18 and DSP21 PMID:12408986 In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. |
| GO:0017017 MAP kinase tyrosine/serine/threonine phosphatase activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: MAP kinase tyrosine/serine/threonine phosphatase activity from InterPro2GO mapping of IPR020420 (atypical DUSP subfamily B). Reason: DUSP21 lacks the kinase-interaction motif and CH2 domain of MAPK phosphatases, showed no activity against MAPKs in cells, and its rat compartment (mitochondrial matrix) does not contain SAPK/JNK. Dephosphorylation of MAPK-derived peptides in vitro does not establish MAPK phosphatase activity; the family-level InterPro mapping over-reaches for this member. Supporting Evidence: PMID:12408986 However, when co-transfected with MAPKs into COS cells, the novel DSPs exhibited no detectable in vivo activity against MAPKs under our conditions. PMID:18385140 DSP18 and DSP21 lack these binding motifs, suggesting a unique substrate recognition motif for these phosphatases PMID:18385140 Similar to the kidney fractions, SAPK/JNK was not detected in mitochondria isolated from testes |
| GO:0030317 flagellated sperm motility | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: Flagellated sperm motility, transferred from mouse Dusp21 via Ensembl Compara. Reason: The mouse source annotations are IDA rows from cryo-EM structure papers that localize DUSP21 inside the sperm doublet microtubule; localization does not show that the phosphatase does any of the work of motility. A Dusp21 knockout has normal sperm motility and fertility, so there is no evidence for this process assignment. Supporting Evidence: PMID:41764189 In contrast, Dusp21-/y spermatozoa exhibited normal morphology, motility, and fertility, mirroring WT phenotypes PMID:41764189 Interestingly, the relatively mild phenotype observed in Dusp21-/y mutants suggests that other sperm phosphatases may compensate for the loss of DUSP21. |
| GO:0030317 flagellated sperm motility | ISO GO_REF:0000121 | MARK AS OVER ANNOTATED | Summary: Flagellated sperm motility by ISO from mouse Dusp21 (MGI:1920797). Reason: The mouse source annotations are IDA rows from cryo-EM structure papers that localize DUSP21 inside the sperm doublet microtubule; localization does not show that the phosphatase does any of the work of motility. A Dusp21 knockout has normal sperm motility and fertility, so there is no evidence for this process assignment. Propagation Review Root cause: SOURCE BAD Failure modes: SOURCE EVIDENCE WEAK Sources checked: MGI:MGI:1920797 · MGI:MGI:1920797 SOURCE BAD The mouse process annotation is derived from structural localization (PMID:37295417, PMID:37989994) and is not supported by the Dusp21 knockout, which shows normal motility (PMID:41764189). Supporting Evidence: PMID:41764189 In contrast, Dusp21-/y spermatozoa exhibited normal morphology, motility, and fertility, mirroring WT phenotypes PMID:41764189 Interestingly, the relatively mild phenotype observed in Dusp21-/y mutants suggests that other sperm phosphatases may compensate for the loss of DUSP21. |
| GO:0036126 sperm flagellum | IEA GO_REF:0000107 | ACCEPT | Summary: Sperm flagellum, transferred from mouse Dusp21 via Ensembl Compara. Reason: Mouse cryo-EM and proteomics place DUSP21 in the sperm flagellar doublet microtubule. The rat gene is a testis-specific rodent ortholog; note human DUSP21 is not found in human sperm DMT, so this is a lineage-specific location, but rat and mouse are both murids. Not directly tested in rat. Supporting Evidence: PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT PMID:37989994 the remaining five MIPs were sperm-specific MIPs that highly expressed in testis tissue31, including Tektin5, CCDC105, DUSP21, CFAP77 and TEX43 |
| GO:0036126 sperm flagellum | ISO GO_REF:0000121 | ACCEPT | Summary: Sperm flagellum by ISO from mouse Dusp21. Reason: Mouse cryo-EM and proteomics place DUSP21 in the sperm flagellar doublet microtubule. The rat gene is a testis-specific rodent ortholog; note human DUSP21 is not found in human sperm DMT, so this is a lineage-specific location, but rat and mouse are both murids. Not directly tested in rat. Supporting Evidence: PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT PMID:37989994 the remaining five MIPs were sperm-specific MIPs that highly expressed in testis tissue31, including Tektin5, CCDC105, DUSP21, CFAP77 and TEX43 |
| GO:0160111 axonemal A tubule inner sheath | IEA GO_REF:0000107 | ACCEPT | Summary: Axonemal A tubule inner sheath, transferred from mouse Dusp21 via Ensembl Compara. Reason: Mouse sperm DMT structures model DUSP21 as a microtubule inner protein in the A-tubule lumen, anchored to tektin filaments. Precise structural location transferred to the murid ortholog; not directly tested in rat. Supporting Evidence: PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT PMID:37989994 the remaining five MIPs were sperm-specific MIPs that highly expressed in testis tissue31, including Tektin5, CCDC105, DUSP21, CFAP77 and TEX43 file:rat/Dusp21/Dusp21-deep-research-manual.md Whether rat sperm DMT contains Dusp21 (as in mouse) has not been tested directly. |
| GO:0160111 axonemal A tubule inner sheath | ISO GO_REF:0000121 | ACCEPT | Summary: Axonemal A tubule inner sheath by ISO from mouse Dusp21. Reason: Mouse sperm DMT structures model DUSP21 as a microtubule inner protein in the A-tubule lumen, anchored to tektin filaments. Precise structural location transferred to the murid ortholog; not directly tested in rat. Supporting Evidence: PMID:41764189 DUSP21, a dual specificity phosphatase anchored to the TEKT3 filament, is present in mouse sperm DMT but absent in human sperm DMT PMID:37989994 the remaining five MIPs were sperm-specific MIPs that highly expressed in testis tissue31, including Tektin5, CCDC105, DUSP21, CFAP77 and TEX43 file:rat/Dusp21/Dusp21-deep-research-manual.md Whether rat sperm DMT contains Dusp21 (as in mouse) has not been tested directly. |
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Download this section (compressed HTML)Q: What are the physiological substrates of DUSP21 in the mitochondrial matrix and in the sperm axoneme?
Q: Are the mitochondrial (Rardin et al. 2008) and axonemal (mouse cryo-EM) localizations of rodent DUSP21 stage-specific pools, or does the 2008 antibody signal need re-evaluation in light of the structural data?
Q: Should the mouse IDA annotations to flagellated sperm motility derived from DMT structure papers be retained given the normal motility of Dusp21 knockout sperm?
Experiment: Substrate-trapping (C105S/D-to-A) DUSP21 pulldowns from rat testis mitochondria and sperm axonemes followed by mass spectrometry, cross-referenced with the hyperphosphorylated sites in Dusp21 knockout sperm.
Experiment: Immuno-EM or cryo-ET of rat sperm flagella and testis sections to determine whether rat Dusp21 occupies the A-tubule MIP site seen in mouse and whether a mitochondrial pool exists in germ cells.
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