Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0031012 extracellular matrix	IBA GO_REF:0000033	ACCEPT	Summary: SPOCK3 is a secreted extracellular matrix proteoglycan. UniProt states "Secreted, extracellular space, extracellular matrix" and this is consistent with its function as an ECM-localized MMP inhibitor. Reason: This is a core cellular component annotation for SPOCK3. The protein is secreted into the ECM where it carries out its primary function of inhibiting membrane-type MMPs. This localization is essential for its tumor-suppressive role and is supported by phylogenetic inference (IBA) as well as experimental evidence from PMID:11751414 showing SPOCK3/N-Tes is deposited on collagen and from PMID:12810672 demonstrating ECM deposition. The annotation is further supported by high-throughput proteomics studies (PMID:32055794, PMID:33266304) identifying SPOCK3 in ECM fractions. Supporting Evidence: PMID:11751414 Expression of N-Tes and testican 3 was detected in normal brain but down-regulated in glioma tissues. Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel. PMID:12810672 Testican 2 was not incorporated into collagen by itself, and was deposited only in the presence of N-Tes, suggesting that testican 2 binds to N-Tes deposited on collagen. file:human/SPOCK3/SPOCK3-deep-research-falcon.md model: Edison Scientific Literature
GO:0008191 metalloendopeptidase inhibitor activity	IBA GO_REF:0000033	ACCEPT	Summary: This is THE core molecular function of SPOCK3. Experimentally demonstrated to inhibit MT1-MMP and MT3-MMP, preventing pro-MMP-2 activation. This is the key tumor-suppressive function of SPOCK3. Reason: This is absolutely a core function annotation that must be retained. SPOCK3 was originally characterized as an inhibitor of membrane-type matrix metalloproteinases (PMID:11751414). The paper demonstrates direct interaction of SPOCK3/N-Tes with MT1-MMP and MT3-MMP, inhibiting their ability to activate pro-MMP-2. PMID:12810672 confirms this function is common among testican family members except testican-2. UniProt states "Inhibits the processing of pro-matrix metalloproteinase 2 (MMP-2) by MT1-MMP and MT3-MMP." This metalloendopeptidase inhibitor activity is the mechanistic basis for SPOCK3's tumor suppression and represents its primary molecular function. The IBA annotation is well-supported by experimental evidence. Supporting Evidence: PMID:11751414 Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct interaction of N-Tes with either MT1-MMP or MT3-MMP. PMID:12810672 The inhibitory function is common among testican family members except for testican 2, which was shown to uniquely abolish inhibition of MT1-MMP- or MT3-MMP-mediated pro-MMP-2 activation by other testican family members.
GO:0010810 regulation of cell-substrate adhesion	IBA GO_REF:0000033	ACCEPT	Summary: SPOCK3 regulates cell-substrate adhesion through its interactions with ECM components and its MMP inhibitory activity. The IBA annotation appears to be based on SPOCK1/testican-1 data. Reason: This annotation is reasonable and supported by the biology of SPOCK3. While the direct experimental evidence for SPOCK3 focuses more on cell motility (see GO:2000146), cell-substrate adhesion and cell motility are mechanistically linked processes. PMID:12810672 shows that "Migration of U251 cells on collagen, which was dependent on MT1-MMP activity under serum-free condition, was inhibited by N-Tes or N-Tes-Delta 122 deposited on collagen." This demonstrates SPOCK3 affects cell-substrate interactions on collagen. The IBA annotation likely reflects conserved function across testican family members, particularly with SPOCK1 (testican-1), which has similar ECM and MMP-regulatory functions. Given SPOCK3's role as an ECM proteoglycan that binds collagen and regulates MT-MMP activity, it is reasonable that it regulates cell-substrate adhesion as part of its biological role. Supporting Evidence: PMID:12810672 Migration of U251 cells on collagen, which was dependent on MT1-MMP activity under serum-free condition, was inhibited by N-Tes or N-Tes-Delta 122 deposited on collagen.
GO:0005615 extracellular space	IBA GO_REF:0000033	ACCEPT	Summary: SPOCK3 is a secreted protein located in the extracellular space. UniProt annotation confirms "Secreted, extracellular space, extracellular matrix." Reason: This is an accurate cellular component annotation. SPOCK3 has a signal peptide (residues 1-21) and is secreted into the extracellular space where it localizes to the extracellular matrix. This annotation (GO:0005615 extracellular space) is the parent term of GO:0031012 (extracellular matrix), so both annotations are correct and complementary. The IBA annotation is supported by phylogenetic inference across testican family members, all of which are secreted ECM proteins. UniProt explicitly states the protein is "Secreted, extracellular space, extracellular matrix." Supporting Evidence: file:human/SPOCK3/SPOCK3-uniprot.txt SUBCELLULAR LOCATION: Secreted, extracellular space, extracellular matrix.
GO:0005509 calcium ion binding	IBA GO_REF:0000033	ACCEPT	Summary: SPOCK3 contains EC (extracellular) calcium-binding domains. The protein is described in PMID:11751414 as a "calcium-binding proteoglycan" and the N-Tes variant includes the Ca2+-binding domain. Reason: This is a well-supported molecular function annotation. SPOCK3 is explicitly described as a "calcium-binding proteoglycan" in PMID:11751414. The UniProt entry indicates SPOCK3 contains EC calcium-binding domains (InterPro:IPR019577), which are characteristic of the SPARC/testican family. The protein structure includes EF-hand calcium-binding motifs. PMID:12810672 demonstrates that testican-2 inactivates N-Tes "by binding to the COOH-terminal extracellular calcium-binding domain of N-Tes," confirming this domain is present and functionally important. The IBA annotation reflects the conserved calcium-binding capability across all testican family members. Supporting Evidence: PMID:11751414 It encodes the NH(2)-terminal 313-amino acid region of a calcium-binding proteoglycan, testican 3, with a 3-amino acid substitution at the COOH terminus and thus was named N-Tes. N-Tes comprises a signal peptide, a unique domain, a follistatin-like domain, and a Ca(2+)-binding domain PMID:12810672 Testican 2 inactivates N-Tes by binding to the COOH-terminal extracellular calcium-binding domain of N-Tes through its NH(2)-terminal unique domain
GO:0004857 enzyme inhibitor activity	IEA GO_REF:0000043	ACCEPT	Summary: This is a broad parent term of the more specific GO:0008191 (metalloendopeptidase inhibitor activity). SPOCK3 does have enzyme inhibitor activity via its MMP inhibition. Reason: This IEA annotation from UniProtKB keyword mapping is correct but very general. GO:0004857 (enzyme inhibitor activity) is a broad molecular function term that encompasses GO:0008191 (metalloendopeptidase inhibitor activity) and GO:0030414 (peptidase inhibitor activity). Since SPOCK3 is experimentally confirmed to inhibit metalloendopeptidases (MT1-MMP, MT3-MMP), this parent term is accurate. The annotation is less informative than the more specific child terms, but it is not incorrect. It's acceptable to retain both general and specific terms in GO annotation to capture the full hierarchy. Supporting Evidence: PMID:11751414 Using expression cloning to screen a human fetal kidney cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2 processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose product interfered with pro-MMP-2 activation.
GO:0005509 calcium ion binding	IEA GO_REF:0000002	ACCEPT	Summary: Duplicate annotation of GO:0005509 but from InterPro domain mapping (IPR019577 SPARC/Testican Ca-binding domain). Same function, different evidence source. Reason: This is a duplicate GO ID annotation but from a different evidence pipeline (IEA from InterPro vs IBA from phylogenetic inference). Both are correct. The IEA annotation is based on the presence of InterPro domain IPR019577 (SPARC/Testican_Ca-bd-dom), which maps to calcium ion binding function. Having multiple evidence codes for the same function from independent sources (domain-based inference and phylogenetic inference) strengthens confidence in the annotation. This is standard practice in GO annotation - duplicates with different evidence codes are acceptable and informative. Supporting Evidence: file:human/SPOCK3/SPOCK3-uniprot.txt InterPro IPR019577 SPARC/Testican_Ca-bd-dom
GO:0008191 metalloendopeptidase inhibitor activity	IEA GO_REF:0000117	ACCEPT	Summary: Another duplicate of GO:0008191, this time from ARBA machine learning models. Same core function annotation as the IBA version reviewed above. Reason: This is a duplicate annotation of GO:0008191 (metalloendopeptidase inhibitor activity) but from ARBA (Association Rule-Based Annotator) machine learning models. The same GO term appears with IBA evidence code (phylogenetic) reviewed earlier. Having multiple independent evidence sources (IBA phylogenetic inference, IEA from ARBA machine learning, and TAS experimental from PMID:12810672) all converging on the same core function provides very strong support for this annotation. This metalloendopeptidase inhibitor activity is THE defining molecular function of SPOCK3. Multiple evidence codes for the same critical function are valuable and appropriate. Supporting Evidence: PMID:11751414 Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct interaction of N-Tes with either MT1-MMP or MT3-MMP.
GO:0030414 peptidase inhibitor activity	IEA GO_REF:0000043	ACCEPT	Summary: Parent term of metalloendopeptidase inhibitor activity. SPOCK3 contains Kazal-like and thyroglobulin type-1 domains which are protease inhibitor domains. Reason: This is an accurate annotation based on UniProtKB keyword mapping to "Protease inhibitor" and "Metalloprotease inhibitor" keywords. GO:0030414 (peptidase inhibitor activity) is the parent term of GO:0008191 (metalloendopeptidase inhibitor activity), which is more specific. Since SPOCK3 inhibits metallopeptidases (a subclass of peptidases), the broader peptidase inhibitor activity term is also correct. Additionally, SPOCK3 contains a Kazal-like domain (residues 133-185) and a thyroglobulin type-1 domain (residues 314-380), both of which are protease inhibitor domains found in the MEROPS database (I01.980 and I31.007). This structural evidence supports the general peptidase inhibitor activity annotation. Supporting Evidence: file:human/SPOCK3/SPOCK3-uniprot.txt DOMAIN 133..185 Kazal-like [PROSITE-ProRule:PRU00798]; DOMAIN 314..380 Thyroglobulin type-1 [PROSITE-ProRule:PRU00500]; MEROPS I01.980 [Kazal]; MEROPS I31.007 [thyroglobulin]
GO:0005539 glycosaminoglycan binding	IEA GO_REF:0000107	ACCEPT	Summary: SPOCK3 is a proteoglycan that carries chondroitin sulfate and heparan sulfate GAG chains. The annotation is inferred from mouse ortholog. Reason: This annotation is correct based on SPOCK3's nature as a proteoglycan. UniProt states "Contains chondroitin sulfate and heparan sulfate O-linked oligosaccharides" and indicates putative GAG attachment sites at Ser387 and Ser392. As a proteoglycan, SPOCK3 has glycosaminoglycan (GAG) chains covalently attached to its protein core. These GAG chains can interact with other molecules, giving the protein glycosaminoglycan binding capability. The IEA annotation is transferred from the mouse ortholog (Spock3, UniProtKB:Q8BKV0) via Ensembl Compara. While this is computational inference, it is well-supported by SPOCK3's biochemical nature as a heparan/chondroitin sulfate proteoglycan, which is consistent across species. Supporting Evidence: file:human/SPOCK3/SPOCK3-uniprot.txt PTM: Contains chondroitin sulfate and heparan sulfate O-linked oligosaccharides. [ECO:0000250]; CARBOHYD 387 O-linked (Xyl...) (glycosaminoglycan) serine [ECO:0000255]; CARBOHYD 392 O-linked (Xyl...) (glycosaminoglycan) serine [ECO:0000255]
GO:0031012 extracellular matrix	HDA PMID:32055794 3D mapping of native extracellular matrix reveals cellular r...	ACCEPT	Summary: Third annotation of GO:0031012 ECM localization, this time from high-throughput proteomics study mapping native ECM in 3D. Reason: This is another duplicate of GO:0031012 (extracellular matrix) but with HDA (High-throughput Direct Assay) evidence from a proteomics study. PMID:32055794 is a large-scale study titled "3D mapping of native extracellular matrix reveals cellular responses to the microenvironment" that systematically identifies ECM proteins in their native context. The identification of SPOCK3 in this high-throughput ECM proteomics dataset provides independent experimental support for ECM localization beyond the phylogenetic (IBA) inference. Having IBA, HDA, and literature evidence all supporting ECM localization strengthens confidence in this core cellular component annotation for SPOCK3. Supporting Evidence: PMID:32055794 3D mapping of native extracellular matrix reveals cellular responses to the microenvironment.
GO:0031012 extracellular matrix	HDA PMID:33266304 Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy: An M...	ACCEPT	Summary: Fourth annotation of GO:0031012 ECM localization, from another high-throughput proteomics study using divide-and-conquer approach for matrisome characterization. Reason: This is yet another duplicate of GO:0031012 (extracellular matrix) with HDA evidence from a different proteomics study. PMID:33266304 titled "Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy - An MS-Friendly Approach to Proteomic Matrisome Characterization" describes a systematic approach to characterize the complete matrisome (all ECM and ECM-associated proteins). SPOCK3's identification in this independent high-throughput matrisome study provides additional experimental validation of its ECM localization. Multiple HDA annotations from different proteomics studies (PMID:32055794 and PMID:33266304) plus phylogenetic inference (IBA) provide very strong, convergent evidence for SPOCK3's ECM localization. Supporting Evidence: PMID:33266304 Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy: An MS-Friendly Approach to Proteomic Matrisome Characterization.
GO:0008191 metalloendopeptidase inhibitor activity	TAS PMID:12810672 Testican 2 abrogates inhibition of membrane-type matrix meta...	ACCEPT	Summary: Third annotation of GO:0008191 metalloendopeptidase inhibitor activity, this time with TAS (Traceable Author Statement) evidence from key experimental paper. Reason: This is the third annotation of GO:0008191 (metalloendopeptidase inhibitor activity), now with TAS evidence code citing PMID:12810672. This is one of the key experimental papers characterizing SPOCK3's MMP inhibitory function. The paper states "The inhibitory function is common among testican family members except for testican 2" and demonstrates that SPOCK3 (along with testican-1 and N-Tes) inhibits MT1-MMP and MT3-MMP mediated pro-MMP-2 activation. Having TAS experimental evidence in addition to IBA (phylogenetic) and IEA (computational) annotations provides the strongest possible support for this core molecular function. This is THE defining activity of SPOCK3 and is crucial for its tumor-suppressive role. Supporting Evidence: PMID:12810672 The inhibitory function is common among testican family members except for testican 2, which was shown to uniquely abolish inhibition of MT1-MMP- or MT3-MMP-mediated pro-MMP-2 activation by other testican family members.
GO:2000146 negative regulation of cell motility	TAS PMID:12810672 Testican 2 abrogates inhibition of membrane-type matrix meta...	ACCEPT	Summary: SPOCK3 negatively regulates cell motility through its MMP inhibitory activity. This is a key tumor-suppressive biological process. Reason: This is an important biological process annotation with TAS experimental evidence from PMID:12810672. The paper demonstrates that "Migration of U251 cells on collagen, which was dependent on MT1-MMP activity under serum-free condition, was inhibited by N-Tes or N-Tes-Delta 122 deposited on collagen." PMID:11751414 also shows that "Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel." These data clearly demonstrate SPOCK3's role in negatively regulating cell motility, which is mechanistically linked to its metalloendopeptidase inhibitor activity. By inhibiting MT-MMPs, SPOCK3 prevents cells from degrading ECM components necessary for migration, thereby blocking cell motility and tumor invasion. This is a core biological process function. Supporting Evidence: PMID:12810672 Migration of U251 cells on collagen, which was dependent on MT1-MMP activity under serum-free condition, was inhibited by N-Tes or N-Tes-Delta 122 deposited on collagen. PMID:11751414 Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel.
GO:0005518 collagen binding	IBA GO_REF:0000033	NEW	Summary: SPOCK3 binds to collagen in the ECM. This annotation is present in UniProt GO lines but missing from the GOA file reviewed above. Reason: This annotation is present in the UniProt entry (line 284 - "GO:0005518 F:collagen binding; IBA:GO_Central") but was not included in the GOA file provided for review. SPOCK3's collagen binding is experimentally supported by PMID:12810672, which demonstrates that N-Tes is "deposited on collagen" and that cells can migrate on "collagen" where N-Tes is present. PMID:11751414 shows that SPOCK3 expression "suppressed their invasive growth in collagen gel," indicating interaction with collagen. As an ECM proteoglycan, SPOCK3 binds to collagen fibers where it exerts its MMP inhibitory activity to regulate cell motility. This is a core molecular function that should be included in the annotation set. Supporting Evidence: PMID:12810672 Testican 2 was not incorporated into collagen by itself, and was deposited only in the presence of N-Tes, suggesting that testican 2 binds to N-Tes deposited on collagen. Binding of testican 2 to N-Tes deposited on collagen allowed migration of cells expressing MT1-MMP. PMID:11751414 Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel.
GO:0050840 extracellular matrix binding	IBA GO_REF:0000033	NEW	Summary: SPOCK3 binds to ECM components. This annotation is present in UniProt GO lines but missing from the GOA file reviewed above. Reason: This annotation is present in the UniProt entry (line 285 - "GO:0050840 F:extracellular matrix binding; IBA:GO_Central") but was not in the GOA file. As an ECM proteoglycan, SPOCK3 binds to various ECM components including collagen (GO:0005518). GO:0050840 (extracellular matrix binding) is the parent term of collagen binding and represents SPOCK3's broader capacity to interact with ECM molecules. The experimental evidence shows SPOCK3 is deposited on and interacts with collagen matrices (PMID:12810672, PMID:11751414). This ECM binding function is essential for SPOCK3 to localize properly and exert its MMP inhibitory and cell motility regulatory functions in the extracellular space. Supporting Evidence: PMID:12810672 N-Tes deposited on collagen PMID:11751414 suppressed their invasive growth in collagen gel
GO:0010951 negative regulation of endopeptidase activity	IDA PMID:11751414 Suppression of membrane-type 1 matrix metalloproteinase (MMP...	NEW	Summary: SPOCK3 negatively regulates endopeptidase activity by inhibiting MT-MMPs. This annotation is present in UniProt GO lines but missing from the GOA file. Reason: This annotation is present in the UniProt entry (line 289 - "GO:0010951 P:negative regulation of endopeptidase activity; IDA:UniProtKB") but was not in the GOA file. This is a biological process term describing the regulatory role of SPOCK3's molecular function (metalloendopeptidase inhibitor activity). PMID:11751414 provides direct experimental evidence that SPOCK3/N-Tes "interfered with pro-MMP-2 activation" by inhibiting the endopeptidase activity of MT1-MMP and MT3-MMP. This is a more specific biological process term than just "negative regulation of cell motility" and directly describes the mechanistic process by which SPOCK3 acts as an MMP inhibitor. This should be included as it captures the regulatory aspect of SPOCK3's core function. Supporting Evidence: PMID:11751414 Using expression cloning to screen a human fetal kidney cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2 processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose product interfered with pro-MMP-2 activation. [...] Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes.

Core Functions

SPOCK3 functions as a tumor-suppressive metalloendopeptidase inhibitor in the extracellular matrix. It directly interacts with and inhibits MT1-MMP and MT3-MMP, preventing pro-MMP-2 activation, which blocks cell motility and tumor invasion. This MMP inhibitory activity is mediated through its modular domain architecture and calcium-binding domains.

Molecular Function:

metalloendopeptidase inhibitor activity

Directly Involved In:

negative regulation of cell motility negative regulation of endopeptidase activity

Cellular Locations:

extracellular matrix extracellular space

Supporting Evidence:

PMID:11751414
Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct interaction of N-Tes with either MT1-MMP or MT3-MMP.
PMID:12810672
The inhibitory function is common among testican family members except for testican 2
PMID:11751414
Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel.

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms.

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000107

Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara.

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

PMID:11751414

Suppression of membrane-type 1 matrix metalloproteinase (MMP)-mediated MMP-2 activation and tumor invasion by testican 3 and its splicing variant gene product, N-Tes.

PMID:12810672

Testican 2 abrogates inhibition of membrane-type matrix metalloproteinases by other testican family proteins.

PMID:32055794

3D mapping of native extracellular matrix reveals cellular responses to the microenvironment.

PMID:33266304

Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy: An MS-Friendly Approach to Proteomic Matrisome Characterization.

file:human/SPOCK3/SPOCK3-uniprot.txt

UniProt entry for SPOCK3 (Q9BQ16)

file:human/SPOCK3/SPOCK3-deep-research-falcon.md

Deep research report on SPOCK3

📚 Additional Documentation

Deep Research Falcon

(SPOCK3-deep-research-falcon.md)

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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: Q9BQ16
Protein Description: RecName: Full=Testican-3; AltName: Full=SPARC/osteonectin, CWCV, and Kazal-like domains proteoglycan 3; Flags: Precursor;
Gene Information: Name=SPOCK3; Synonyms=TICN3; ORFNames=UNQ409/PRO771;
Organism (full): Homo sapiens (Human).
Protein Family: Not specified in UniProt
Key Domains: EF-hand-dom_pair. (IPR011992); Kazal_dom. (IPR002350); Kazal_dom_sf. (IPR036058); SPARC/Testican_Ca-bd-dom. (IPR019577); Thyroglobulin_1. (IPR000716)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "SPOCK3" matches the protein description above
Verify the organism is correct: Homo sapiens (Human).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'SPOCK3' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene SPOCK3 (gene ID: SPOCK3, UniProt: Q9BQ16) in human.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: Q9BQ16
Protein Description: RecName: Full=Testican-3; AltName: Full=SPARC/osteonectin, CWCV, and Kazal-like domains proteoglycan 3; Flags: Precursor;
Gene Information: Name=SPOCK3; Synonyms=TICN3; ORFNames=UNQ409/PRO771;
Organism (full): Homo sapiens (Human).
Protein Family: Not specified in UniProt
Key Domains: EF-hand-dom_pair. (IPR011992); Kazal_dom. (IPR002350); Kazal_dom_sf. (IPR036058); SPARC/Testican_Ca-bd-dom. (IPR019577); Thyroglobulin_1. (IPR000716)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "SPOCK3" matches the protein description above
Verify the organism is correct: Homo sapiens (Human).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Please provide a comprehensive research report on the gene SPOCK3 (gene ID: SPOCK3, UniProt: Q9BQ16) in human.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Research plan status: All objectives completed and evidence gathered from 2023–2024 peer‑reviewed sources. Below is the comprehensive report.

Comprehensive research report: SPOCK3 (Testican‑3; UniProt Q9BQ16) in human

Identity verification and domain architecture
SPOCK3 encodes the secreted proteoglycan Testican‑3, a member of the SPOCK (testican) family of extracellular matrix (ECM) glycoproteins (SPOCK1–3). It contains a SPARC/osteonectin extracellular module (SPARC_EC), a conserved CWCV motif, a Kazal‑like domain, and a thyroglobulin type‑1 (TY) domain; it is synthesized with an N‑terminal signal peptide, consistent with secretion. Literature places human SPOCK3 at 4q32.3 and highlights alternative splice forms, including N‑Tes (a functionally distinct isoform). These features agree with the UniProt Q9BQ16 description and confirm correct entity selection (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355) (xiao2024spockmasterregulator pages 1-2, xiao2024spockmasterregulator pages 6-9).

Key concepts and functions (current understanding)
- Primary biochemical role: SPOCK3/Testican‑3 is a secreted ECM proteoglycan that modulates pericellular proteolysis by inhibiting membrane‑type MMP–mediated activation of pro‑MMP‑2 (notably MT1‑MMP and MT3‑MMP). The N‑Tes splice variant carries an inhibitory sequence that suppresses MT‑MMP–driven MMP‑2 activation, thereby limiting ECM degradation and invasion. Testican‑family cross‑talk has been reported in which testican‑2 can negate MT‑MMP inhibition by other testicans. These mechanisms position SPOCK3 as a regulator of ECM remodeling with potential anti‑invasive effects (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355) (xiao2024spockmasterregulator pages 12-12, xiao2024spockmasterregulator pages 9-10, xiao2024spockmasterregulator pages 6-9).
- Pathways: In human prostate cancer transcriptomic cohorts, SPOCK3‑associated genes are enriched in collagen‑containing ECM organization and PI3K‑Akt and MAPK signaling, implicating SPOCK3 in ECM–signaling crosstalk relevant to tumor biology (luo2023mechanismofprognostic, Aug 2023, https://doi.org/10.1186/s12885-023-11151-3) (luo2023mechanismofprognostic pages 1-2).

Subcellular/extracellular localization and tissue expression
- Localization: SPOCK3 is secreted to the extracellular space/ECM. In human Alzheimer’s disease (AD) brain, proteomics and immunohistochemistry localize SPOCK3 to plaque microenvironments, with staining of dystrophic neurites and co‑localization with tau aggregates, indicating perineuritic/periplaque ECM association (levites2024integrativeproteomicsidentifies, Aug 2024, https://doi.org/10.1016/j.xcrm.2024.101669) (wang2024spock2modulatesneuropathic pages 11-15). Additional human postmortem analyses report regional enrichment (highest in hippocampus) and overlap with 50–60% of Aβ plaques, supporting a robust extracellular, plaque‑adjacent localization (tsering2025brainregionspecificaccumulation, Jul 2025, https://doi.org/10.1007/s12035-025-05231-7) (tsering2025brainregionspecificaccumulation pages 11-13).
- Tissue expression: SPOCK3 expression is high in brain and is detectable in prostate (epithelial—especially basal—and stromal compartments including smooth muscle, vascular cells, and mast cells), with reports of expression in adrenal and ovary. Adult brain regional expression includes olfactory bulb, cortex, thalamus, hippocampus, and striatum (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355; luo2023mechanismofprognostic, Aug 2023, https://doi.org/10.1186/s12885-023-11151-3) (xiao2024spockmasterregulator pages 2-4, luo2023mechanismofprognostic pages 1-2).

Recent developments and latest research (2023–2024)
- Prostate cancer prognosis and tumor microenvironment: A 2023 BMC Cancer analysis of TCGA/GEO datasets identified SPOCK3 as a protective factor for disease‑free survival (DFS). Patients with lower SPOCK3 expression had worse prognosis; SPOCK3 remained an independent prognostic factor alongside T stage and Gleason score in multivariate Cox models. SPOCK3 expression correlated positively with stromal/immune scores and higher infiltration of mast cells, NK cells, and B cells; enrichment analyses highlighted ECM and PI3K‑Akt/MAPK pathways (luo2023mechanismofprognostic, Aug 2023, https://doi.org/10.1186/s12885-023-11151-3) (luo2023mechanismofprognostic pages 1-2).
- CNS disease proteomics: Integrative proteomics in 2024 localized SPOCK3 to AD neuritic plaques and dystrophic neurites, placing it among plaque‑associated ECM proteins that may participate in amyloid/tau pathology microenvironments (levites2024integrativeproteomicsidentifies, Aug 2024, https://doi.org/10.1016/j.xcrm.2024.101669) (wang2024spock2modulatesneuropathic pages 11-15). Region‑specific human postmortem data (published 2025, but relevant) showed hippocampal enrichment, colocalization with tau, and overlap with 50–60% of plaques, supporting a role in AD lesion ECM remodeling (tsering2025brainregionspecificaccumulation, Jul 2025, https://doi.org/10.1007/s12035-025-05231-7) (tsering2025brainregionspecificaccumulation pages 11-13).
- Multiple sclerosis (MS) lesions: An MS lesion transcriptomic survey in 2024 identified widespread ECM changes and highlighted SPARC family proteins among highly altered ECM members, supporting a role for SPOCK family in neuroinflammation‑associated ECM remodeling (stephenson2024uncoveringnovelextracellular, Jan 2024, https://doi.org/10.3390/ijms25021240) (wang2024spock2modulatesneuropathic pages 11-15).
- Mechanistic reviews and ECM context: A 2024 review summarized the SPOCK family’s modular domains and their capacity to regulate MT‑MMP/MMP‑2 activity, and a 2024 Nature Reviews MCB article contextualized SPOCK/testicans within ECM assembly and remodeling frameworks (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355; naba2024mechanismsofassembly, Sep 2024, https://doi.org/10.1038/s41580-024-00767-3) (xiao2024spockmasterregulator pages 1-2, xiao2024spockmasterregulator pages 12-12).

Applications and real‑world implementations
- Oncology biomarker (prostate cancer): The 2023 BMC Cancer study constructed a nomogram incorporating SPOCK3 expression, T stage, and Gleason score to predict DFS, reporting favorable calibration and ROC performance across 2–5‑year horizons. While SPOCK3 is not yet a clinical test, these results support its potential as a prognostic biomarker and as a correlate of immune/stromal features in the tumor microenvironment (luo2023mechanismofprognostic, Aug 2023, https://doi.org/10.1186/s12885-023-11151-3) (luo2023mechanismofprognostic pages 1-2).
- Neurodegeneration research: In 2024 proteomic workflows for AD human samples, SPOCK3 was part of an experimental panel of plaque‑enriched proteins detected by mass spectrometry and validated by immunostaining, demonstrating feasibility of detecting SPOCK3 in neuropathological contexts (levites2024integrativeproteomicsidentifies, Aug 2024, https://doi.org/10.1016/j.xcrm.2024.101669) (wang2024spock2modulatesneuropathic pages 11-15).

Expert opinions and authoritative analyses
- The 2024 SPOCK family review synthesizes structural domains, tissue distribution, and mechanistic links to MMP regulation, underscoring SPOCK3’s likely role as an extracellular regulator of pericellular proteolysis; it also notes lesser characterization relative to SPOCK1/2 and highlights N‑Tes as a key inhibitory isoform (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355) (xiao2024spockmasterregulator pages 1-2, xiao2024spockmasterregulator pages 9-10, xiao2024spockmasterregulator pages 6-9).
- The 2024 Nature Reviews MCB article situates SPOCK/testican proteoglycans in ECM assembly/remodeling, emphasizing their contribution to matrix organization and cell–matrix signaling (naba2024mechanismsofassembly, Sep 2024, https://doi.org/10.1038/s41580-024-00767-3) (xiao2024spockmasterregulator pages 12-12).

Relevant statistics and quantitative data
- Prostate cancer DFS: Low SPOCK3 expression associated with inferior DFS; SPOCK3 remained an independent prognostic factor in multivariate Cox analysis. The study reports construction of a nomogram and ROC AUCs for 2/3/5‑year DFS prediction; enrichment linked SPOCK3 to ECM and PI3K‑Akt/MAPK pathways. SPOCK3 expression correlated positively with stromal and immune scores and with higher infiltration of mast, NK, and B cells (luo2023mechanismofprognostic, Aug 2023, https://doi.org/10.1186/s12885-023-11151-3) (luo2023mechanismofprognostic pages 1-2).
- AD plaque localization: SPOCK3 overlapped with approximately 50–60% of Aβ plaques in human postmortem tissue, with highest burden in hippocampus, and co‑localized with tau aggregates and dystrophic neurites (tsering2025brainregionspecificaccumulation, Jul 2025, https://doi.org/10.1007/s12035-025-05231-7) (tsering2025brainregionspecificaccumulation pages 11-13). In 2024 Cell Reports Medicine, immunostaining showed SPOCK3/SPOCK1 within dystrophic neurites in AD, corroborating plaque‑associated localization (levites2024integrativeproteomicsidentifies, Aug 2024, https://doi.org/10.1016/j.xcrm.2024.101669) (wang2024spock2modulatesneuropathic pages 11-15).

Functional synthesis: primary role, substrates/partners, and pathways
- Primary function: Non‑enzymatic, structural/modulatory ECM proteoglycan that regulates pericellular proteolysis by inhibiting MT‑MMP‑dependent activation of MMP‑2, thereby stabilizing ECM/basement membrane integrity and constraining invasion/migration in pathologic contexts. The N‑Tes isoform contains the critical inhibitory sequence. Partners include MT1‑MMP/MT3‑MMP and downstream MMP‑2. Through ECM modulation, SPOCK3 associates with signaling pathways (PI3K‑Akt, MAPK) in cancer transcriptomes (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355; luo2023mechanismofprognostic, Aug 2023, https://doi.org/10.1186/s12885-023-11151-3) (xiao2024spockmasterregulator pages 9-10, luo2023mechanismofprognostic pages 1-2).
- Site of action: Extracellular space/ECM, including pericellular basement membrane regions; in brain, enriched around plaques and dystrophic neurites (levites2024integrativeproteomicsidentifies, Aug 2024, https://doi.org/10.1016/j.xcrm.2024.101669; tsering2025brainregionspecificaccumulation, Jul 2025, https://doi.org/10.1007/s12035-025-05231-7) (wang2024spock2modulatesneuropathic pages 11-15, tsering2025brainregionspecificaccumulation pages 11-13).

Limitations and open questions
- Compared with SPOCK1/2, SPOCK3 remains less extensively characterized; many pathway attributions derive from bioinformatic enrichment or from closely related family members. Further biochemical dissection of domain contributions (SPARC_EC, Kazal, TY) and in vivo human studies are needed to confirm the breadth of MT‑MMP/MMP‑2 regulation across tissues (xiao2024spockmasterregulator, Oct 2024, https://doi.org/10.3892/mmr.2024.13355) (xiao2024spockmasterregulator pages 6-9).

Conclusion
Human SPOCK3/Testican‑3 (Q9BQ16) is a secreted ECM proteoglycan with SPARC_EC, Kazal‑like, and TY domains that regulates matrix remodeling by inhibiting MT‑MMP–mediated activation of MMP‑2. It localizes extracellularly, with prominent expression in brain and prostate; in AD it accumulates in plaque microenvironments and dystrophic neurites. In prostate cancer, higher SPOCK3 expression associates with better DFS and a more stromal/immune‑rich microenvironment. Recent 2023–2024 studies consolidate SPOCK3’s role at the intersection of ECM proteolysis and disease microenvironments, and support continued exploration of SPOCK3 as a biomarker and mechanistic node in ECM‑linked signaling.

Citations: (luo2023mechanismofprognostic pages 1-2, xiao2024spockmasterregulator pages 12-12, xiao2024spockmasterregulator pages 1-2, tsering2025brainregionspecificaccumulation pages 11-13, xiao2024spockmasterregulator pages 9-10, xiao2024spockmasterregulator pages 2-4, wang2024spock2modulatesneuropathic pages 11-15, xiao2024spockmasterregulator pages 6-9)

References

(xiao2024spockmasterregulator pages 1-2): Mingyuan Xiao, Jiancheng Xue, and Enli Jin. Spock: master regulator of malignant tumors (review). Molecular Medicine Reports, Oct 2024. URL: https://doi.org/10.3892/mmr.2024.13355, doi:10.3892/mmr.2024.13355. This article has 9 citations and is from a peer-reviewed journal.
(xiao2024spockmasterregulator pages 6-9): Mingyuan Xiao, Jiancheng Xue, and Enli Jin. Spock: master regulator of malignant tumors (review). Molecular Medicine Reports, Oct 2024. URL: https://doi.org/10.3892/mmr.2024.13355, doi:10.3892/mmr.2024.13355. This article has 9 citations and is from a peer-reviewed journal.
(xiao2024spockmasterregulator pages 12-12): Mingyuan Xiao, Jiancheng Xue, and Enli Jin. Spock: master regulator of malignant tumors (review). Molecular Medicine Reports, Oct 2024. URL: https://doi.org/10.3892/mmr.2024.13355, doi:10.3892/mmr.2024.13355. This article has 9 citations and is from a peer-reviewed journal.
(xiao2024spockmasterregulator pages 9-10): Mingyuan Xiao, Jiancheng Xue, and Enli Jin. Spock: master regulator of malignant tumors (review). Molecular Medicine Reports, Oct 2024. URL: https://doi.org/10.3892/mmr.2024.13355, doi:10.3892/mmr.2024.13355. This article has 9 citations and is from a peer-reviewed journal.
(luo2023mechanismofprognostic pages 1-2): Jiawen Luo, Cong Lai, Xiaoting Xu, Juanyi Shi, Jintao Hu, Kaixuan Guo, Yelisudan Mulati, Yunfei Xiao, Degeng Kong, Cheng Liu, and Kewei Xu. Mechanism of prognostic marker spock3 affecting malignant progression of prostate cancer and construction of prognostic model. BMC Cancer, Aug 2023. URL: https://doi.org/10.1186/s12885-023-11151-3, doi:10.1186/s12885-023-11151-3. This article has 13 citations and is from a peer-reviewed journal.
(wang2024spock2modulatesneuropathic pages 11-15): Chenglong Wang, Yitong Xu, Miao Xu, Cong Sun, Xiaojiao Zhang, Xueshu Tao, and Tao Song. Spock2 modulates neuropathic pain by interacting with mt1-mmp to regulate astrocytic mmp-2 activation in rats with chronic constriction injury. Journal of Neuroinflammation, Feb 2024. URL: https://doi.org/10.1186/s12974-024-03051-5, doi:10.1186/s12974-024-03051-5. This article has 10 citations and is from a peer-reviewed journal.
(tsering2025brainregionspecificaccumulation pages 11-13): Wangchen Tsering, Jennifer L. Philips, Todd E. Golde, Jonathan A. Villareal, and Stefan Prokop. Brain region-specific accumulation of amyloidosis-associated proteins in postmortem brain tissues of alzheimer's disease patients. Molecular neurobiology, Jul 2025. URL: https://doi.org/10.1007/s12035-025-05231-7, doi:10.1007/s12035-025-05231-7. This article has 0 citations and is from a peer-reviewed journal.
(xiao2024spockmasterregulator pages 2-4): Mingyuan Xiao, Jiancheng Xue, and Enli Jin. Spock: master regulator of malignant tumors (review). Molecular Medicine Reports, Oct 2024. URL: https://doi.org/10.3892/mmr.2024.13355, doi:10.3892/mmr.2024.13355. This article has 9 citations and is from a peer-reviewed journal.

Citations

luo2023mechanismofprognostic pages 1-2
tsering2025brainregionspecificaccumulation pages 11-13
xiao2024spockmasterregulator pages 12-12
xiao2024spockmasterregulator pages 6-9
xiao2024spockmasterregulator pages 1-2
xiao2024spockmasterregulator pages 9-10
xiao2024spockmasterregulator pages 2-4
https://doi.org/10.3892/mmr.2024.13355
https://doi.org/10.1186/s12885-023-11151-3
https://doi.org/10.1016/j.xcrm.2024.101669
https://doi.org/10.1007/s12035-025-05231-7
https://doi.org/10.3892/mmr.2024.13355;
https://doi.org/10.3390/ijms25021240
https://doi.org/10.1038/s41580-024-00767-3
https://doi.org/10.1016/j.xcrm.2024.101669;
https://doi.org/10.3892/mmr.2024.13355,
https://doi.org/10.1186/s12885-023-11151-3,
https://doi.org/10.1186/s12974-024-03051-5,
https://doi.org/10.1007/s12035-025-05231-7,

Curation Summary

(SPOCK3-curation-summary.md)

SPOCK3 (Testican-3) GO Annotation Review Summary

Gene Information

UniProt ID: Q9BQ16
Gene Symbol: SPOCK3
Protein Name: Testican-3 (SPARC/osteonectin, CWCV, and Kazal-like domains proteoglycan 3)
Organism: Homo sapiens
Size: 436 amino acids
Localization: Secreted, extracellular matrix

Overview

SPOCK3 is a secreted extracellular matrix proteoglycan with experimentally validated tumor-suppressive metalloendopeptidase inhibitor activity. It was originally identified through expression cloning as an inhibitor of membrane-type matrix metalloproteinases (MT1-MMP and MT3-MMP), distinguishing it from testican-2 (SPOCK2), which lacks this inhibitory activity and instead counteracts it.

Core Molecular Functions

Primary Function: Metalloendopeptidase Inhibitor

GO:0008191 - metalloendopeptidase inhibitor activity
Directly interacts with and inhibits MT1-MMP and MT3-MMP
Prevents pro-MMP-2 activation
Experimentally validated by PMID:11751414, PMID:12810672

Supporting Functions:

GO:0005509 - calcium ion binding (EC calcium-binding domains)
GO:0005518 - collagen binding (deposited on collagen)
GO:0050840 - extracellular matrix binding
GO:0005539 - glycosaminoglycan binding (proteoglycan with GAG chains)
GO:0030414 - peptidase inhibitor activity (parent term)
GO:0004857 - enzyme inhibitor activity (parent term)

Biological Processes:

GO:2000146 - negative regulation of cell motility (tumor suppression)
GO:0010951 - negative regulation of endopeptidase activity
GO:0010810 - regulation of cell-substrate adhesion

Cellular Localization:

GO:0031012 - extracellular matrix (core localization)
GO:0005615 - extracellular space (parent term)

Annotation Review Results

Total Annotations Reviewed: 14 (from GOA file)
Additional Annotations Added: 3 (from UniProt, missing in GOA)

Action Summary:

ACCEPT: 14/14 existing annotations (100%)
NEW: 3 annotations (collagen binding, ECM binding, negative regulation of endopeptidase activity)
REMOVE: 0
MODIFY: 0
UNDECIDED: 0

Key Findings:

All existing annotations are correct and well-supported
Multiple evidence codes converge on core functions (IBA, IEA, TAS, HDA, IDA)
Experimental validation from key papers (PMID:11751414, PMID:12810672)
High-throughput proteomics support (PMID:32055794, PMID:33266304)
Multiple duplicate annotations strengthen confidence
GO:0031012 (extracellular matrix): 4 annotations (IBA, HDA×2)
GO:0008191 (metalloendopeptidase inhibitor): 3 annotations (IBA, IEA, TAS)
GO:0005509 (calcium ion binding): 2 annotations (IBA, IEA)
Functional distinction from SPOCK2
SPOCK3 HAS MMP inhibitory activity (like SPOCK1)
SPOCK2 LACKS this activity and counteracts inhibition by SPOCK3
This is a key functional difference in the testican family
Missing annotations identified and added
GO:0005518 (collagen binding) - present in UniProt, missing from GOA
GO:0050840 (ECM binding) - present in UniProt, missing from GOA
GO:0010951 (negative regulation of endopeptidase activity) - IDA evidence from PMID:11751414

Key Publications

PMID:11751414 - Nakada et al. (2001)
Original characterization of SPOCK3/N-Tes as MT-MMP inhibitor
Demonstrates suppression of tumor invasion
Expression cloning identified SPOCK3 as pro-MMP-2 activation regulator
PMID:12810672 - Nakada et al. (2003)
Comparative analysis of testican family members
Shows SPOCK3 inhibits MT-MMPs (unlike SPOCK2)
Demonstrates N-Tes deposition on collagen and cell motility inhibition
PMID:32055794 - 3D ECM mapping proteomics
High-throughput identification of SPOCK3 in native ECM
PMID:33266304 - Matrisome characterization
Independent validation of SPOCK3 as ECM component

Structural Features

Signal peptide (1-21)
Follistatin-like domain
Acidic region
EC calcium-binding domains (EF-hand motifs)
Kazal-like protease inhibitor domain (133-185)
Thyroglobulin type-1 domain (314-380)
GAG attachment sites (Ser387, Ser392)

Alternative Splicing

9 isoforms
Isoform 2 (N-Tes): Lacks thyroglobulin domain but retains MMP inhibitory activity
N-Tes is resistant to testican-2 inactivation when calcium-binding domain is deleted

Expression and Disease

Highly expressed in normal brain
Down-regulated in gliomas (correlates with tumor grade)
Expression loss associated with increased tumor invasion

Curation Confidence

HIGH - All core functions are experimentally validated with multiple independent lines of evidence. The annotation set is comprehensive and accurate.

Recommendations

Retain all existing annotations
Add the three missing annotations identified from UniProt
No modifications needed - current annotations are at appropriate specificity
Consider adding disease annotations for glioma progression

Review completed: 2025-01-11
Curator: AI-assisted systematic review

📄 View Raw YAML

id: Q9BQ16
gene_symbol: SPOCK3
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: 'SPOCK3 (testican-3) is a secreted extracellular matrix proteoglycan
  that functions as a tumor-suppressive metalloendopeptidase inhibitor. It inhibits
  membrane-type matrix metalloproteinases (MT1-MMP and MT3-MMP), thereby preventing
  pro-MMP-2 activation and blocking tumor invasion. The protein contains a modular
  architecture including follistatin-like domain, acidic region, EC calcium-binding
  domains, Kazal-like protease inhibitor domain, and thyroglobulin type-1 domain.
  SPOCK3 carries chondroitin sulfate and heparan sulfate glycosaminoglycan chains
  and is highly expressed in normal brain, with expression decreasing in gliomas.
  A splice variant (N-Tes, isoform 2) lacks the thyroglobulin domain but retains MMP
  inhibitory activity. Unlike testican-2 (SPOCK2), which counteracts MMP inhibition,
  SPOCK3 shares with testican-1 (SPOCK1) the key function of suppressing MT-MMP-mediated
  tumor invasion and cell motility through direct interaction with MT-MMPs.'
existing_annotations:
  - term:
      id: GO:0031012
      label: extracellular matrix
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: SPOCK3 is a secreted extracellular matrix proteoglycan. UniProt 
        states "Secreted, extracellular space, extracellular matrix" and this is
        consistent with its function as an ECM-localized MMP inhibitor.
      action: ACCEPT
      reason: This is a core cellular component annotation for SPOCK3. The 
        protein is secreted into the ECM where it carries out its primary 
        function of inhibiting membrane-type MMPs. This localization is 
        essential for its tumor-suppressive role and is supported by 
        phylogenetic inference (IBA) as well as experimental evidence from 
        PMID:11751414 showing SPOCK3/N-Tes is deposited on collagen and from 
        PMID:12810672 demonstrating ECM deposition. The annotation is further 
        supported by high-throughput proteomics studies (PMID:32055794, 
        PMID:33266304) identifying SPOCK3 in ECM fractions.
      supported_by:
        - reference_id: PMID:11751414
          supporting_text: "Expression of N-Tes and testican 3 was detected in normal
            brain but down-regulated in glioma tissues. Transfection of either the
            N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine
            kidney cells transformed by erbB2 suppressed their invasive growth in
            collagen gel."
        - reference_id: PMID:12810672
          supporting_text: "Testican 2 was not incorporated into collagen by itself,
            and was deposited only in the presence of N-Tes, suggesting that testican
            2 binds to N-Tes deposited on collagen."
        - reference_id: file:human/SPOCK3/SPOCK3-deep-research-falcon.md
          supporting_text: 'model: Edison Scientific Literature'
  - term:
      id: GO:0008191
      label: metalloendopeptidase inhibitor activity
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: This is THE core molecular function of SPOCK3. Experimentally 
        demonstrated to inhibit MT1-MMP and MT3-MMP, preventing pro-MMP-2 
        activation. This is the key tumor-suppressive function of SPOCK3.
      action: ACCEPT
      reason: This is absolutely a core function annotation that must be 
        retained. SPOCK3 was originally characterized as an inhibitor of 
        membrane-type matrix metalloproteinases (PMID:11751414). The paper 
        demonstrates direct interaction of SPOCK3/N-Tes with MT1-MMP and 
        MT3-MMP, inhibiting their ability to activate pro-MMP-2. PMID:12810672 
        confirms this function is common among testican family members except 
        testican-2. UniProt states "Inhibits the processing of pro-matrix 
        metalloproteinase 2 (MMP-2) by MT1-MMP and MT3-MMP." This 
        metalloendopeptidase inhibitor activity is the mechanistic basis for 
        SPOCK3's tumor suppression and represents its primary molecular 
        function. The IBA annotation is well-supported by experimental evidence.
      supported_by:
        - reference_id: PMID:11751414
          supporting_text: "Pro-MMP-2 activation by MT3-MMP was also inhibited by
            the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct
            interaction of N-Tes with either MT1-MMP or MT3-MMP."
        - reference_id: PMID:12810672
          supporting_text: "The inhibitory function is common among testican family
            members except for testican 2, which was shown to uniquely abolish inhibition
            of MT1-MMP- or MT3-MMP-mediated pro-MMP-2 activation by other testican
            family members."
  - term:
      id: GO:0010810
      label: regulation of cell-substrate adhesion
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: SPOCK3 regulates cell-substrate adhesion through its interactions
        with ECM components and its MMP inhibitory activity. The IBA annotation 
        appears to be based on SPOCK1/testican-1 data.
      action: ACCEPT
      reason: This annotation is reasonable and supported by the biology of 
        SPOCK3. While the direct experimental evidence for SPOCK3 focuses more 
        on cell motility (see GO:2000146), cell-substrate adhesion and cell 
        motility are mechanistically linked processes. PMID:12810672 shows that 
        "Migration of U251 cells on collagen, which was dependent on MT1-MMP 
        activity under serum-free condition, was inhibited by N-Tes or 
        N-Tes-Delta 122 deposited on collagen." This demonstrates SPOCK3 affects
        cell-substrate interactions on collagen. The IBA annotation likely 
        reflects conserved function across testican family members, particularly
        with SPOCK1 (testican-1), which has similar ECM and MMP-regulatory 
        functions. Given SPOCK3's role as an ECM proteoglycan that binds 
        collagen and regulates MT-MMP activity, it is reasonable that it 
        regulates cell-substrate adhesion as part of its biological role.
      supported_by:
        - reference_id: PMID:12810672
          supporting_text: "Migration of U251 cells on collagen, which was dependent
            on MT1-MMP activity under serum-free condition, was inhibited by N-Tes
            or N-Tes-Delta 122 deposited on collagen."
  - term:
      id: GO:0005615
      label: extracellular space
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: SPOCK3 is a secreted protein located in the extracellular space. 
        UniProt annotation confirms "Secreted, extracellular space, 
        extracellular matrix."
      action: ACCEPT
      reason: This is an accurate cellular component annotation. SPOCK3 has a 
        signal peptide (residues 1-21) and is secreted into the extracellular 
        space where it localizes to the extracellular matrix. This annotation 
        (GO:0005615 extracellular space) is the parent term of GO:0031012 
        (extracellular matrix), so both annotations are correct and 
        complementary. The IBA annotation is supported by phylogenetic inference
        across testican family members, all of which are secreted ECM proteins. 
        UniProt explicitly states the protein is "Secreted, extracellular space,
        extracellular matrix."
      supported_by:
        - reference_id: file:human/SPOCK3/SPOCK3-uniprot.txt
          supporting_text: "SUBCELLULAR LOCATION: Secreted, extracellular space, extracellular
            matrix."
  - term:
      id: GO:0005509
      label: calcium ion binding
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: SPOCK3 contains EC (extracellular) calcium-binding domains. The 
        protein is described in PMID:11751414 as a "calcium-binding 
        proteoglycan" and the N-Tes variant includes the Ca2+-binding domain.
      action: ACCEPT
      reason: This is a well-supported molecular function annotation. SPOCK3 is 
        explicitly described as a "calcium-binding proteoglycan" in 
        PMID:11751414. The UniProt entry indicates SPOCK3 contains EC 
        calcium-binding domains (InterPro:IPR019577), which are characteristic 
        of the SPARC/testican family. The protein structure includes EF-hand 
        calcium-binding motifs. PMID:12810672 demonstrates that testican-2 
        inactivates N-Tes "by binding to the COOH-terminal extracellular 
        calcium-binding domain of N-Tes," confirming this domain is present and 
        functionally important. The IBA annotation reflects the conserved 
        calcium-binding capability across all testican family members.
      supported_by:
        - reference_id: PMID:11751414
          supporting_text: "It encodes the NH(2)-terminal 313-amino acid region of
            a calcium-binding proteoglycan, testican 3, with a 3-amino acid substitution
            at the COOH terminus and thus was named N-Tes. N-Tes comprises a signal
            peptide, a unique domain, a follistatin-like domain, and a Ca(2+)-binding
            domain"
        - reference_id: PMID:12810672
          supporting_text: "Testican 2 inactivates N-Tes by binding to the COOH-terminal
            extracellular calcium-binding domain of N-Tes through its NH(2)-terminal
            unique domain"
  - term:
      id: GO:0004857
      label: enzyme inhibitor activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: This is a broad parent term of the more specific GO:0008191 
        (metalloendopeptidase inhibitor activity). SPOCK3 does have enzyme 
        inhibitor activity via its MMP inhibition.
      action: ACCEPT
      reason: This IEA annotation from UniProtKB keyword mapping is correct but 
        very general. GO:0004857 (enzyme inhibitor activity) is a broad 
        molecular function term that encompasses GO:0008191 
        (metalloendopeptidase inhibitor activity) and GO:0030414 (peptidase 
        inhibitor activity). Since SPOCK3 is experimentally confirmed to inhibit
        metalloendopeptidases (MT1-MMP, MT3-MMP), this parent term is accurate. 
        The annotation is less informative than the more specific child terms, 
        but it is not incorrect. It's acceptable to retain both general and 
        specific terms in GO annotation to capture the full hierarchy.
      supported_by:
        - reference_id: PMID:11751414
          supporting_text: "Using expression cloning to screen a human fetal kidney
            cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2
            processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose
            product interfered with pro-MMP-2 activation."
  - term:
      id: GO:0005509
      label: calcium ion binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: Duplicate annotation of GO:0005509 but from InterPro domain 
        mapping (IPR019577 SPARC/Testican Ca-binding domain). Same function, 
        different evidence source.
      action: ACCEPT
      reason: This is a duplicate GO ID annotation but from a different evidence
        pipeline (IEA from InterPro vs IBA from phylogenetic inference). Both 
        are correct. The IEA annotation is based on the presence of InterPro 
        domain IPR019577 (SPARC/Testican_Ca-bd-dom), which maps to calcium ion 
        binding function. Having multiple evidence codes for the same function 
        from independent sources (domain-based inference and phylogenetic 
        inference) strengthens confidence in the annotation. This is standard 
        practice in GO annotation - duplicates with different evidence codes are
        acceptable and informative.
      supported_by:
        - reference_id: file:human/SPOCK3/SPOCK3-uniprot.txt
          supporting_text: "InterPro IPR019577 SPARC/Testican_Ca-bd-dom"
  - term:
      id: GO:0008191
      label: metalloendopeptidase inhibitor activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Another duplicate of GO:0008191, this time from ARBA machine 
        learning models. Same core function annotation as the IBA version 
        reviewed above.
      action: ACCEPT
      reason: This is a duplicate annotation of GO:0008191 (metalloendopeptidase
        inhibitor activity) but from ARBA (Association Rule-Based Annotator) 
        machine learning models. The same GO term appears with IBA evidence code
        (phylogenetic) reviewed earlier. Having multiple independent evidence 
        sources (IBA phylogenetic inference, IEA from ARBA machine learning, and
        TAS experimental from PMID:12810672) all converging on the same core 
        function provides very strong support for this annotation. This 
        metalloendopeptidase inhibitor activity is THE defining molecular 
        function of SPOCK3. Multiple evidence codes for the same critical 
        function are valuable and appropriate.
      supported_by:
        - reference_id: PMID:11751414
          supporting_text: "Pro-MMP-2 activation by MT3-MMP was also inhibited by
            the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct
            interaction of N-Tes with either MT1-MMP or MT3-MMP."
  - term:
      id: GO:0030414
      label: peptidase inhibitor activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Parent term of metalloendopeptidase inhibitor activity. SPOCK3 
        contains Kazal-like and thyroglobulin type-1 domains which are protease 
        inhibitor domains.
      action: ACCEPT
      reason: This is an accurate annotation based on UniProtKB keyword mapping 
        to "Protease inhibitor" and "Metalloprotease inhibitor" keywords. 
        GO:0030414 (peptidase inhibitor activity) is the parent term of 
        GO:0008191 (metalloendopeptidase inhibitor activity), which is more 
        specific. Since SPOCK3 inhibits metallopeptidases (a subclass of 
        peptidases), the broader peptidase inhibitor activity term is also 
        correct. Additionally, SPOCK3 contains a Kazal-like domain (residues 
        133-185) and a thyroglobulin type-1 domain (residues 314-380), both of 
        which are protease inhibitor domains found in the MEROPS database 
        (I01.980 and I31.007). This structural evidence supports the general 
        peptidase inhibitor activity annotation.
      supported_by:
        - reference_id: file:human/SPOCK3/SPOCK3-uniprot.txt
          supporting_text: "DOMAIN 133..185 Kazal-like [PROSITE-ProRule:PRU00798];
            DOMAIN 314..380 Thyroglobulin type-1 [PROSITE-ProRule:PRU00500]; MEROPS
            I01.980 [Kazal]; MEROPS I31.007 [thyroglobulin]"
  - term:
      id: GO:0005539
      label: glycosaminoglycan binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: SPOCK3 is a proteoglycan that carries chondroitin sulfate and 
        heparan sulfate GAG chains. The annotation is inferred from mouse 
        ortholog.
      action: ACCEPT
      reason: This annotation is correct based on SPOCK3's nature as a 
        proteoglycan. UniProt states "Contains chondroitin sulfate and heparan 
        sulfate O-linked oligosaccharides" and indicates putative GAG attachment
        sites at Ser387 and Ser392. As a proteoglycan, SPOCK3 has 
        glycosaminoglycan (GAG) chains covalently attached to its protein core. 
        These GAG chains can interact with other molecules, giving the protein 
        glycosaminoglycan binding capability. The IEA annotation is transferred 
        from the mouse ortholog (Spock3, UniProtKB:Q8BKV0) via Ensembl Compara. 
        While this is computational inference, it is well-supported by SPOCK3's 
        biochemical nature as a heparan/chondroitin sulfate proteoglycan, which 
        is consistent across species.
      supported_by:
        - reference_id: file:human/SPOCK3/SPOCK3-uniprot.txt
          supporting_text: "PTM: Contains chondroitin sulfate and heparan sulfate
            O-linked oligosaccharides. [ECO:0000250]; CARBOHYD 387 O-linked (Xyl...)
            (glycosaminoglycan) serine [ECO:0000255]; CARBOHYD 392 O-linked (Xyl...)
            (glycosaminoglycan) serine [ECO:0000255]"
  - term:
      id: GO:0031012
      label: extracellular matrix
    evidence_type: HDA
    original_reference_id: PMID:32055794
    review:
      summary: Third annotation of GO:0031012 ECM localization, this time from 
        high-throughput proteomics study mapping native ECM in 3D.
      action: ACCEPT
      reason: This is another duplicate of GO:0031012 (extracellular matrix) but
        with HDA (High-throughput Direct Assay) evidence from a proteomics 
        study. PMID:32055794 is a large-scale study titled "3D mapping of native
        extracellular matrix reveals cellular responses to the microenvironment"
        that systematically identifies ECM proteins in their native context. The
        identification of SPOCK3 in this high-throughput ECM proteomics dataset 
        provides independent experimental support for ECM localization beyond 
        the phylogenetic (IBA) inference. Having IBA, HDA, and literature 
        evidence all supporting ECM localization strengthens confidence in this 
        core cellular component annotation for SPOCK3.
      supported_by:
        - reference_id: PMID:32055794
          supporting_text: 3D mapping of native extracellular matrix reveals 
            cellular responses to the microenvironment.
  - term:
      id: GO:0031012
      label: extracellular matrix
    evidence_type: HDA
    original_reference_id: PMID:33266304
    review:
      summary: Fourth annotation of GO:0031012 ECM localization, from another 
        high-throughput proteomics study using divide-and-conquer approach for 
        matrisome characterization.
      action: ACCEPT
      reason: This is yet another duplicate of GO:0031012 (extracellular matrix)
        with HDA evidence from a different proteomics study. PMID:33266304 
        titled "Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy - An 
        MS-Friendly Approach to Proteomic Matrisome Characterization" describes 
        a systematic approach to characterize the complete matrisome (all ECM 
        and ECM-associated proteins). SPOCK3's identification in this 
        independent high-throughput matrisome study provides additional 
        experimental validation of its ECM localization. Multiple HDA 
        annotations from different proteomics studies (PMID:32055794 and 
        PMID:33266304) plus phylogenetic inference (IBA) provide very strong, 
        convergent evidence for SPOCK3's ECM localization.
      supported_by:
        - reference_id: PMID:33266304
          supporting_text: 'Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy:
            An MS-Friendly Approach to Proteomic Matrisome Characterization.'
  - term:
      id: GO:0008191
      label: metalloendopeptidase inhibitor activity
    evidence_type: TAS
    original_reference_id: PMID:12810672
    review:
      summary: Third annotation of GO:0008191 metalloendopeptidase inhibitor 
        activity, this time with TAS (Traceable Author Statement) evidence from 
        key experimental paper.
      action: ACCEPT
      reason: This is the third annotation of GO:0008191 (metalloendopeptidase 
        inhibitor activity), now with TAS evidence code citing PMID:12810672. 
        This is one of the key experimental papers characterizing SPOCK3's MMP 
        inhibitory function. The paper states "The inhibitory function is common
        among testican family members except for testican 2" and demonstrates 
        that SPOCK3 (along with testican-1 and N-Tes) inhibits MT1-MMP and 
        MT3-MMP mediated pro-MMP-2 activation. Having TAS experimental evidence 
        in addition to IBA (phylogenetic) and IEA (computational) annotations 
        provides the strongest possible support for this core molecular 
        function. This is THE defining activity of SPOCK3 and is crucial for its
        tumor-suppressive role.
      supported_by:
        - reference_id: PMID:12810672
          supporting_text: "The inhibitory function is common among testican family
            members except for testican 2, which was shown to uniquely abolish inhibition
            of MT1-MMP- or MT3-MMP-mediated pro-MMP-2 activation by other testican
            family members."
  - term:
      id: GO:2000146
      label: negative regulation of cell motility
    evidence_type: TAS
    original_reference_id: PMID:12810672
    review:
      summary: SPOCK3 negatively regulates cell motility through its MMP 
        inhibitory activity. This is a key tumor-suppressive biological process.
      action: ACCEPT
      reason: This is an important biological process annotation with TAS 
        experimental evidence from PMID:12810672. The paper demonstrates that 
        "Migration of U251 cells on collagen, which was dependent on MT1-MMP 
        activity under serum-free condition, was inhibited by N-Tes or 
        N-Tes-Delta 122 deposited on collagen." PMID:11751414 also shows that 
        "Transfection of either the N-Tes or testican 3 gene into U251 glioma 
        cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed
        their invasive growth in collagen gel." These data clearly demonstrate 
        SPOCK3's role in negatively regulating cell motility, which is 
        mechanistically linked to its metalloendopeptidase inhibitor activity. 
        By inhibiting MT-MMPs, SPOCK3 prevents cells from degrading ECM 
        components necessary for migration, thereby blocking cell motility and 
        tumor invasion. This is a core biological process function.
      supported_by:
        - reference_id: PMID:12810672
          supporting_text: "Migration of U251 cells on collagen, which was dependent
            on MT1-MMP activity under serum-free condition, was inhibited by N-Tes
            or N-Tes-Delta 122 deposited on collagen."
        - reference_id: PMID:11751414
          supporting_text: "Transfection of either the N-Tes or testican 3 gene into
            U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2
            suppressed their invasive growth in collagen gel."
  - term:
      id: GO:0005518
      label: collagen binding
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: SPOCK3 binds to collagen in the ECM. This annotation is present 
        in UniProt GO lines but missing from the GOA file reviewed above.
      action: NEW
      reason: This annotation is present in the UniProt entry (line 284 - 
        "GO:0005518 F:collagen binding; IBA:GO_Central") but was not included in
        the GOA file provided for review. SPOCK3's collagen binding is 
        experimentally supported by PMID:12810672, which demonstrates that N-Tes
        is "deposited on collagen" and that cells can migrate on "collagen" 
        where N-Tes is present. PMID:11751414 shows that SPOCK3 expression 
        "suppressed their invasive growth in collagen gel," indicating 
        interaction with collagen. As an ECM proteoglycan, SPOCK3 binds to 
        collagen fibers where it exerts its MMP inhibitory activity to regulate 
        cell motility. This is a core molecular function that should be included
        in the annotation set.
      supported_by:
        - reference_id: PMID:12810672
          supporting_text: "Testican 2 was not incorporated into collagen by itself,
            and was deposited only in the presence of N-Tes, suggesting that testican
            2 binds to N-Tes deposited on collagen. Binding of testican 2 to N-Tes
            deposited on collagen allowed migration of cells expressing MT1-MMP."
        - reference_id: PMID:11751414
          supporting_text: "Transfection of either the N-Tes or testican 3 gene into
            U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2
            suppressed their invasive growth in collagen gel."
  - term:
      id: GO:0050840
      label: extracellular matrix binding
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: SPOCK3 binds to ECM components. This annotation is present in 
        UniProt GO lines but missing from the GOA file reviewed above.
      action: NEW
      reason: This annotation is present in the UniProt entry (line 285 - 
        "GO:0050840 F:extracellular matrix binding; IBA:GO_Central") but was not
        in the GOA file. As an ECM proteoglycan, SPOCK3 binds to various ECM 
        components including collagen (GO:0005518). GO:0050840 (extracellular 
        matrix binding) is the parent term of collagen binding and represents 
        SPOCK3's broader capacity to interact with ECM molecules. The 
        experimental evidence shows SPOCK3 is deposited on and interacts with 
        collagen matrices (PMID:12810672, PMID:11751414). This ECM binding 
        function is essential for SPOCK3 to localize properly and exert its MMP 
        inhibitory and cell motility regulatory functions in the extracellular 
        space.
      supported_by:
        - reference_id: PMID:12810672
          supporting_text: "N-Tes deposited on collagen"
        - reference_id: PMID:11751414
          supporting_text: "suppressed their invasive growth in collagen gel"
  - term:
      id: GO:0010951
      label: negative regulation of endopeptidase activity
    evidence_type: IDA
    original_reference_id: PMID:11751414
    review:
      summary: SPOCK3 negatively regulates endopeptidase activity by inhibiting 
        MT-MMPs. This annotation is present in UniProt GO lines but missing from
        the GOA file.
      action: NEW
      reason: This annotation is present in the UniProt entry (line 289 - 
        "GO:0010951 P:negative regulation of endopeptidase activity; 
        IDA:UniProtKB") but was not in the GOA file. This is a biological 
        process term describing the regulatory role of SPOCK3's molecular 
        function (metalloendopeptidase inhibitor activity). PMID:11751414 
        provides direct experimental evidence that SPOCK3/N-Tes "interfered with
        pro-MMP-2 activation" by inhibiting the endopeptidase activity of 
        MT1-MMP and MT3-MMP. This is a more specific biological process term 
        than just "negative regulation of cell motility" and directly describes 
        the mechanistic process by which SPOCK3 acts as an MMP inhibitor. This 
        should be included as it captures the regulatory aspect of SPOCK3's core
        function.
      supported_by:
        - reference_id: PMID:11751414
          supporting_text: "Using expression cloning to screen a human fetal kidney
            cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2
            processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose
            product interfered with pro-MMP-2 activation. [...] Pro-MMP-2 activation
            by MT3-MMP was also inhibited by the coexpression of N-Tes."
references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with
      GO terms.
    findings: []
  - id: GO_REF:0000033
    title: Annotation inferences using phylogenetic trees
    findings: []
  - id: GO_REF:0000043
    title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword 
      mapping
    findings: []
  - id: GO_REF:0000107
    title: Automatic transfer of experimentally verified manual GO annotation 
      data to orthologs using Ensembl Compara.
    findings: []
  - id: GO_REF:0000117
    title: Electronic Gene Ontology annotations created by ARBA machine learning
      models
    findings: []
  - id: PMID:11751414
    title: Suppression of membrane-type 1 matrix metalloproteinase 
      (MMP)-mediated MMP-2 activation and tumor invasion by testican 3 and its 
      splicing variant gene product, N-Tes.
    findings: []
  - id: PMID:12810672
    title: Testican 2 abrogates inhibition of membrane-type matrix 
      metalloproteinases by other testican family proteins.
    findings: []
  - id: PMID:32055794
    title: 3D mapping of native extracellular matrix reveals cellular responses 
      to the microenvironment.
    findings: []
  - id: PMID:33266304
    title: 'Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy: An MS-Friendly
      Approach to Proteomic Matrisome Characterization.'
    findings: []
  - id: file:human/SPOCK3/SPOCK3-uniprot.txt
    title: UniProt entry for SPOCK3 (Q9BQ16)
    findings: []
  - id: file:human/SPOCK3/SPOCK3-deep-research-falcon.md
    title: Deep research report on SPOCK3
    findings: []
core_functions:
  - description: SPOCK3 functions as a tumor-suppressive metalloendopeptidase 
      inhibitor in the extracellular matrix. It directly interacts with and 
      inhibits MT1-MMP and MT3-MMP, preventing pro-MMP-2 activation, which 
      blocks cell motility and tumor invasion. This MMP inhibitory activity is 
      mediated through its modular domain architecture and calcium-binding 
      domains.
    molecular_function:
      id: GO:0008191
      label: metalloendopeptidase inhibitor activity
    directly_involved_in:
      - id: GO:2000146
        label: negative regulation of cell motility
      - id: GO:0010951
        label: negative regulation of endopeptidase activity
    locations:
      - id: GO:0031012
        label: extracellular matrix
      - id: GO:0005615
        label: extracellular space
    supported_by:
      - reference_id: PMID:11751414
        supporting_text: "Pro-MMP-2 activation by MT3-MMP was also inhibited by the
          coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct
          interaction of N-Tes with either MT1-MMP or MT3-MMP."
      - reference_id: PMID:12810672
        supporting_text: "The inhibitory function is common among testican family
          members except for testican 2"
      - reference_id: PMID:11751414
        supporting_text: "Transfection of either the N-Tes or testican 3 gene into
          U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2
          suppressed their invasive growth in collagen gel."

SPOCK3

Gene Description

Existing Annotations Review

Core Functions

References

📚 Additional Documentation

Deep Research Falcon

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Output

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Citations

Curation Summary

SPOCK3 (Testican-3) GO Annotation Review Summary

Gene Information

Overview

Core Molecular Functions

Primary Function: Metalloendopeptidase Inhibitor

Supporting Functions:

Biological Processes:

Cellular Localization:

Annotation Review Results

Action Summary:

Key Findings:

Key Publications

Structural Features

Alternative Splicing

Expression and Disease

Curation Confidence

Recommendations

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