GO Term	Evidence	Action	Reason
GO:0005615 extracellular space	IBA GO_REF:0000033	ACCEPT	Summary: CRISP2 is a secretory protein that is released into extracellular space. The IBA annotation is based on phylogenetic inference across the CRISP family, which are characterized as secreted proteins. Reason: The annotation is correct and well-supported. CRISP2 contains a signal peptide (residues 1-21) and is annotated as "Secreted" in UniProt. The deep research confirms CRISP2 "is predicted to be active in the extracellular space, consistent with its secretory nature" and localizes to the acrosome and flagellum of sperm cells, which are extracellular compartments. The IBA evidence provides strong phylogenetic support across orthologous CRISP family members. Supporting Evidence: PMID:8665901 CRISP-2/TPX1 transcripts are...detected mainly in the testis and also in the epididymis file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is primarily localized to the acrosome and flagellum of sperm cells. It is predicted to be active in the extracellular space, consistent with its secretory nature file:human/CRISP2/CRISP2-uniprot.txt SUBCELLULAR LOCATION: Secreted file:human/CRISP2/CRISP2-deep-research-falcon.md In ejaculated sperm, CRISP2 is reported in the cytoplasmic droplet, flagellum, and EqS, consistent with roles in motility and gamete fusion
GO:0005576 extracellular region	IEA GO_REF:0000120	ACCEPT	Summary: This is a broad extracellular localization term assigned by automated evidence based on InterPro domain signatures and UniProt subcellular location annotation. Reason: The annotation is correct as CRISP2 is a secreted protein found in extracellular regions. While GO:0005615 (extracellular space) is more specific, GO:0005576 (extracellular region) is also accurate and represents a valid parent term. The IEA annotation is appropriately conservative, providing broad localization information based on sequence features and subcellular location keywords. Having both the specific term (GO:0005615) and broader term (GO:0005576) is acceptable and provides complete annotation coverage. Supporting Evidence: GO_REF:0000120 Combined Automated Annotation using Multiple IEA Methods based on InterPro:IPR018244 and UniProtKB-SubCell:SL-0243 file:human/CRISP2/CRISP2-uniprot.txt SUBCELLULAR LOCATION: Secreted file:human/CRISP2/CRISP2-deep-research-falcon.md CRISPs as typically two-domain proteins comprising an N-terminal CAP domain plus a C-terminal cysteine-rich CRISP domain
GO:0005615 extracellular space	TAS PMID:8665901 The human cysteine-rich secretory protein (CRISP) family. Pr...	ACCEPT	Summary: This annotation is supported by the foundational characterization paper for the human CRISP family by Kraetzschmar et al. 1996, which described CRISP2 tissue distribution and confirmed it as a secreted protein. Reason: The TAS (Traceable Author Statement) annotation is well-founded. PMID:8665901 is the seminal paper characterizing CRISP2 (referred to as TPX1 in that work) as a secretory protein with testis and epididymis expression. The paper states "CRISP-2 cDNA corresponds to the previously described TPX1 form" and describes tissue distribution indicating secretory nature. While the abstract does not explicitly state "extracellular space," the characterization of CRISP proteins as secretory proteins with cysteine-rich domains supports extracellular localization. This represents core literature-based evidence for CRISP2 localization. Supporting Evidence: PMID:8665901 CRISP-2/TPX1 transcripts are...detected mainly in the testis and also in the epididymis... We report the isolation and characterisation of cDNAs encoding three different, human members of the cysteine-rich secretory protein (CRISP) family. file:human/CRISP2/CRISP2-deep-research-falcon.md In human epididymis, CRISP2 staining is observed in sperm within the lumen (including a dense spot at the basal head region and along the flagellum), while the epididymal epithelium is negative
GO:0005246 calcium channel regulator activity	NAS	NEW	Summary: Added to align core_functions with existing annotations. Reason: Core function term not present in existing_annotations. Supporting Evidence: file:human/CRISP2/CRISP2-uniprot.txt May regulate some ion channels' activity and thereby regulate calcium fluxes during sperm capacitation. file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is predicted to regulate the activity of certain ion channels, particularly those involved in calcium fluxes during sperm capacitation, a process essential for fertilization file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is involved in the acrosome reaction, a key step in fertilization where the sperm releases enzymes to penetrate the egg file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is primarily localized to the acrosome and flagellum of sperm cells file:human/CRISP2/CRISP2-deep-research-falcon.md Review-level synthesis places CRISP2 in sperm Ca2+ signaling through ryanodine receptor (RyR)-mediated Ca2+ release and broader ion-channel modulation file:human/CRISP2/CRISP2-deep-research-falcon.md A 2023 ejaculate-based shotgun proteomics study explicitly annotates CRISP2 as potentially regulating ion channels and thereby calcium fluxes during sperm capacitation
GO:0001669 acrosomal vesicle	NAS	NEW	Summary: Added to align core_functions with existing annotations. Reason: Core function term not present in existing_annotations. Supporting Evidence: file:human/CRISP2/CRISP2-uniprot.txt May regulate some ion channels' activity and thereby regulate calcium fluxes during sperm capacitation. file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is predicted to regulate the activity of certain ion channels, particularly those involved in calcium fluxes during sperm capacitation, a process essential for fertilization file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is involved in the acrosome reaction, a key step in fertilization where the sperm releases enzymes to penetrate the egg file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is primarily localized to the acrosome and flagellum of sperm cells file:human/CRISP2/CRISP2-deep-research-falcon.md Late elongated spermatids: CRISP2 also seen in the flagellum and the equatorial segment (EqS) of the acrosome file:human/CRISP2/CRISP2-deep-research-falcon.md In ejaculated sperm, CRISP2 is reported in the cytoplasmic droplet, flagellum, and EqS**, consistent with roles in motility and gamete fusion
GO:0048240 sperm capacitation	NAS	NEW	Summary: Added to align core_functions with existing annotations. Reason: Core function term not present in existing_annotations. Supporting Evidence: file:human/CRISP2/CRISP2-uniprot.txt May regulate some ion channels' activity and thereby regulate calcium fluxes during sperm capacitation. file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is predicted to regulate the activity of certain ion channels, particularly those involved in calcium fluxes during sperm capacitation, a process essential for fertilization file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is involved in the acrosome reaction, a key step in fertilization where the sperm releases enzymes to penetrate the egg file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is primarily localized to the acrosome and flagellum of sperm cells file:human/CRISP2/CRISP2-deep-research-falcon.md A 2023 ejaculate-based shotgun proteomics study explicitly annotates CRISP2 as potentially regulating ion channels and thereby calcium fluxes during sperm capacitation
GO:0007340 acrosome reaction	NAS	NEW	Summary: Added to align core_functions with existing annotations. Reason: Core function term not present in existing_annotations. Supporting Evidence: file:human/CRISP2/CRISP2-uniprot.txt May regulate some ion channels' activity and thereby regulate calcium fluxes during sperm capacitation. file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is predicted to regulate the activity of certain ion channels, particularly those involved in calcium fluxes during sperm capacitation, a process essential for fertilization file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is involved in the acrosome reaction, a key step in fertilization where the sperm releases enzymes to penetrate the egg file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md CRISP2 is primarily localized to the acrosome and flagellum of sperm cells file:human/CRISP2/CRISP2-deep-research-falcon.md Late elongated spermatids: CRISP2 also seen in the flagellum and the equatorial segment (EqS)** of the acrosome
GO:0032934 sterol binding	NAS	NEW	Summary: Added based on 2024 biochemical evidence that the CRISP2 CAP domain binds cholesterol sulfate and mediates sterol export in a yeast assay; activity is inhibited by A1BG binding in a Mg2+-dependent manner. Reason: Novel mechanistic activity supported by PMID:39433128 (El Atab et al. 2024, J Biol Chem) demonstrating direct sterol binding via the CAP domain. This activity is not in current GOA but represents a credible biochemical function from a domain-leading peer-reviewed journal. Supporting Evidence: PMID:39433128 Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2 file:human/CRISP2/CRISP2-deep-research-falcon.md biochemical evidence that CRISP2 participates in sterol binding and sterol export in a yeast-based functional model and that this activity can be strongly regulated by A1BG file:human/CRISP2/CRISP2-deep-research-falcon.md Coexpression of A1BG with CRISP2 (or related CAP proteins) reduced sterol secretion by >50% in vivo (yeast export assay)

Deep Research

Falcon

(CRISP2-deep-research-falcon.md)

Research report: Human **CRISP2** (UniProt **P16562**) functional annotation Falcon Edison Scientific Literature 44 citations 2 artifacts 2026-05-29T17:38:22.825844

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000050 The table row for CRISP2 (P16562) is found in Table 1 on page 8 of the document. This row includes the gene name (CRISP2), protein (image/png)

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.

Research report: Human CRISP2 (UniProt P16562) functional annotation

0) Scope, identity verification, and ambiguity check

Target identity (verified)

The requested target—human CRISP2 (cysteine-rich secretory protein 2; CRISP-2; TPX-1/TPX1; CT36)—is correctly matched to UniProt accession P16562. A human sperm study explicitly maps mass-spectrometry peptides onto the two UniProt isoforms P16562-1 and P16562-2, confirming that the reviewed literature is aligned to the same protein identity (masai2025novelinsightsinto pages 11-11, masai2025novelinsightsinto pages 14-15). Reported aliases in the human study include TPX1 and AA1 (masai2025novelinsightsinto pages 38-40), consistent with the provided UniProt description.

Family/domain context

CRISP2 belongs to the CRISP family within the broader CAP superfamily (also called SCP/PR-1/Antigen 5). Authoritative reviews define CRISPs as typically two-domain proteins comprising an N-terminal CAP domain plus a C-terminal cysteine-rich CRISP domain (CRD/ICR + hinge) stabilized by multiple disulfide bonds; the N-terminal CAP domain is often implicated in protein–protein/cell–cell interactions in reproduction, while the C-terminal CRISP domain has been linked to ion-channel regulatory activity (gibbs2008thecapsuperfamily pages 4-4, gibbs2008thecapsuperfamily pages 3-4, gibbs2008thecapsuperfamily pages 4-5).

1) Key concepts and definitions (current understanding)

1.1 CAP superfamily and CRISP domain architecture

The CAP domain is a conserved, disulfide-stabilized module widely distributed across taxa and associated with diverse extracellular and reproductive functions (gibbs2008thecapsuperfamily pages 3-4).
CRISPs are a CAP-subfamily defined by an additional C-terminal CRISP domain with a characteristic conserved cysteine pattern (10 strictly conserved cysteines forming 5 disulfide bonds) and a hinge region with distinctive cysteine spacing (gibbs2008thecapsuperfamily pages 4-5).

1.2 Functional framing of CRISP2

CRISP2 is best understood as a non-enzymatic structural/interaction protein in sperm biology rather than a metabolic enzyme: it is positioned in reviews as a reproductive tract–associated CAP/CRISP protein implicated in sperm development, capacitation-associated signaling, and gamete interaction, with proposed ion-channel/Ca2+ modulation roles (gibbs2008thecapsuperfamily pages 17-17, gibbs2008thecapsuperfamily pages 18-19).

2) Expression and localization (where CRISP2 acts)

2.1 Tissue and cell-type specificity

An authoritative review notes CRISP2 is produced during spermatogenesis and localizes to key sperm compartments (acrosome, accessory tail structures, developing germ-cell membrane) (gibbs2008thecapsuperfamily pages 17-17). A recent human-focused primary study further refines this with direct tissue imaging and biochemical characterization (masai2025novelinsightsinto pages 1-1).

2.2 Subcellular localization during human spermatogenesis

In human testis sections, immunostaining shows CRISP2 signal across germ-cell stages:
- Primary spermatocytes: faint nuclear puncta.
- Round spermatids: more intense, homogeneous nuclear signal.
- Early elongated spermatids: intense nuclear spots with additional cytoplasmic signal.
- Late elongated spermatids: CRISP2 also seen in the flagellum and the equatorial segment (EqS) of the acrosome; late nuclei may appear negative, possibly reflecting chromatin condensation.
These observations were supported by antibody controls and confocal imaging (masai2025novelinsightsinto pages 6-7, masai2025novelinsightsinto pages 7-8).

2.3 Localization in epididymis and ejaculated sperm

In human epididymis, CRISP2 staining is observed in sperm within the lumen (including a dense spot at the basal head region and along the flagellum), while the epididymal epithelium is negative (masai2025novelinsightsinto pages 5-6). In ejaculated sperm, CRISP2 is reported in the cytoplasmic droplet, flagellum, and EqS, consistent with roles in motility and gamete fusion (masai2025novelinsightsinto pages 1-1).

3) Molecular mechanism and pathways

3.1 Ion-channel/Ca2+ signaling links (conceptual and proteomics-supported)

Review-level synthesis places CRISP2 in sperm Ca2+ signaling through ryanodine receptor (RyR)-mediated Ca2+ release and broader ion-channel modulation (gibbs2008thecapsuperfamily pages 17-17, gibbs2008thecapsuperfamily pages 18-19). A 2023 ejaculate-based shotgun proteomics study explicitly annotates CRISP2 as potentially regulating ion channels and thereby calcium fluxes during sperm capacitation (shkrigunov2023theapplicationof pages 8-9).

3.2 Sterol binding/export activity and regulation by A1BG (2024 mechanistic advance)

A major 2024 development is biochemical evidence that CRISP2 participates in sterol binding and sterol export in a yeast-based functional model and that this activity can be strongly regulated by A1BG:
- Binding partner/regulator: Human A1BG binds CRISP2 with high affinity (MST Kd values reported around 13.72 ± 2.5 nM; also ~10.3 ± 2.4 nM under Mg2+ conditions) (atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 12-13).
- Functional inhibition: Coexpression of A1BG with CRISP2 (or related CAP proteins) reduced sterol secretion by >50% in vivo (yeast export assay) (atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 1-2).
- Ligand binding: CRISP2 binds cholesterol sulfate with reported Kd values ranging from low micromolar to nanomolar depending on assay conditions; binding is blocked by A1BG (atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 12-13, atab2024alpha1bglycoprotein(a1bg) pages 9-11).
- Cation dependence: The A1BG–CRISP2 interaction is Mg2+-dependent; Zn2+ cannot substitute in restoring binding after EDTA chelation (atab2024alpha1bglycoprotein(a1bg) pages 11-12, atab2024alpha1bglycoprotein(a1bg) pages 12-13).

Mechanistically, these findings reinforce the CAP-domain concept of ligand binding and extend CRISP2 beyond purely “ion-channel regulator” framing toward lipid/sterol handling that may be relevant in reproductive tract fluids and sperm membranes (atab2024alpha1bglycoprotein(a1bg) pages 1-2, atab2024alpha1bglycoprotein(a1bg) pages 2-4).

3.3 Protein complexes and interaction landscape

A human immunoprecipitation/MS study detected P16562 peptides repeatedly and lists co-detected proteins (including ACR and ACRBP) in CRISP2-associated material, supporting that CRISP2 participates in stable complexes in sperm extracts (masai2025novelinsightsinto pages 38-40).
Review-level evidence reports CRISP2 binding partners including MAP3K11/MLK3 (co-localizing in the acrosome) and GGN1 (in the tail), supporting a model in which CRISP2 is integrated into signaling/structural complexes (gibbs2008thecapsuperfamily pages 17-17).

4) Recent developments and latest research (prioritizing 2023–2024)

4.1 Quantitative detection of CRISP2 in human ejaculate/sperm proteomics (2023)

A 2023 study evaluating ejaculate-based shotgun proteomics quantified CRISP2 (P16562) across ejaculate, seminal plasma, and spermatozoa:
- Validated unique peptides: ejaculate 11; plasma 30; spermatozoa 8.
- NSAF (spectrum counting): ejaculate 0.49; plasma 0.383; spermatozoa 0.474.
The same source summarizes CRISP2 as potentially regulating ion-channel activity and Ca2+ flux during capacitation (shkrigunov2023theapplicationof pages 8-9). A table image excerpt corroborates these values (shkrigunov2023theapplicationof media 5dc187ee).

4.2 miRNA-linked regulation in infertility phenotypes (2024 synthesis)

A 2024 Frontiers in Endocrinology review compiling clinical miRNA studies summarizes that:
- miR-27b is reported upregulated in a semen-based comparison (n=24 vs 24) and is listed as targeting CRISP2, associated with effects on sperm morphology and progressive motility (shi2024micrornasinspermatogenesis pages 3-4).
- The review also states that high miR-27b expression is associated with reduced progressive motility and shows a negative association with CRISP2 protein levels (shi2024micrornasinspermatogenesis pages 4-5).
Evidence in the review is largely summarized (often without effect sizes in table form), so the quantitative strength of these associations depends on the original primary studies (shi2024micrornasinspermatogenesis pages 4-5, shi2024micrornasinspermatogenesis pages 19-20).

4.3 Clinical context for biomarker translation (2024)

A 2024 prospective seminal plasma proteomics study on azoospermia provides clinically relevant statistics (not CRISP2-specific but directly relevant to implementation of testis-derived protein markers):
- Azoospermia affects nearly 2% of men and accounts for 5–20% of male infertility.
- NOA comprises about 90% of azoospermia cases.
- Sperm retrieval success is >90% in obstructive azoospermia but only ~50% in NOA.
This underpins the value of non-invasive seminal plasma protein biomarkers to avoid unnecessary surgery and to triage patients for retrieval attempts (fietz2024proteomicbiomarkersin pages 2-3, fietz2024proteomicbiomarkersin pages 1-2).

5) Current applications and real-world implementation

5.1 Male infertility screening panels (proteomics)

CRISP2 is already operationally used as a measured component in high-throughput LC-MS/MS datasets of ejaculate, seminal plasma, and spermatozoa, enabling quantitative comparisons and pathway enrichment in male infertility screening pipelines (shkrigunov2023theapplicationof pages 8-9).

5.2 Seminal plasma proteomics for clinical decision support in azoospermia

Seminal plasma proteomics is being developed as a non-invasive tool to distinguish OA vs NOA and predict intratesticular sperm presence to rationalize surgery recommendations (fietz2024proteomicbiomarkersin pages 2-3, fietz2024proteomicbiomarkersin pages 1-2). While CRISP2 is not the primary marker highlighted in the pages examined, it is cited among infertility-related proteins in referenced work within this literature context (fietz2024proteomicbiomarkersin pages 12-12).

6) Expert opinion and authoritative analysis (translation readiness)

A 2024 expert review argues that sperm/ejaculate proteomics has substantial potential to improve diagnostics, guide ART, and identify non-hormonal contraceptive targets; however, translation is constrained by the need for reliable, reproducible, affordable assays and extensive validation and regulatory work (parkes2024bringingproteomicsto pages 28-29, parkes2024bringingproteomicsto pages 6-7). The authors highlight a persistent gap between biomarker discovery and clinical adoption and stress the importance of integrating proteomics with clinical phenotypes, genetics, and robust in vivo validation (parkes2024bringingproteomicsto pages 29-31).

7) Relevant statistics and quantitative data summary

CRISP2 abundance in ejaculate-based proteomics (2023): validated unique peptides 11/30/8 and NSAF 0.49/0.383/0.474 (ejaculate/plasma/spermatozoa) (shkrigunov2023theapplicationof pages 8-9, shkrigunov2023theapplicationof media 5dc187ee).
A1BG–CRISP2 binding affinity (2024): MST Kd ≈ 13.72 ± 2.5 nM (and ~10.3 ± 2.4 nM under Mg2+ conditions) (atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 12-13).
A1BG inhibition of CRISP2-mediated sterol export (2024): >50% reduction in secretion in yeast assays (atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 1-2).
Clinical burden relevant to biomarker deployment (2024): azoospermia nearly 2% of men; 5–20% of male infertility; NOA ~90% of azoospermia; NOA retrieval ~50% vs OA >90% (fietz2024proteomicbiomarkersin pages 2-3, fietz2024proteomicbiomarkersin pages 1-2).

8) Evidence-grounded summary table

Category	Key points	Evidence type (review/primary/proteomics)	Top citations (pqac-IDs)
Identity/domains	Human CRISP2 is UniProt P16562; recent human sperm work explicitly maps peptides to isoforms P16562-1 and P16562-2. It is a CAP superfamily/CRISP-family protein with an N-terminal CAP domain and a C-terminal cysteine-rich CRISP domain (including hinge/ICR features); the family is linked to ion-channel regulation and reproduction.	Primary + review	(masai2025novelinsightsinto pages 11-11, masai2025novelinsightsinto pages 38-40, gibbs2008thecapsuperfamily pages 3-4, gibbs2008thecapsuperfamily pages 4-4, gibbs2008thecapsuperfamily pages 4-5)
Expression	CRISP2 is the mammalian CRISP most tightly associated with testicular germ cells and spermatogenesis. In human tissue, expression is seen through spermatogenic stages and not in epididymal epithelium; in sperm proteomics it is repeatedly detected in ejaculated sperm.	Primary + review + proteomics	(masai2025novelinsightsinto pages 11-12, masai2025novelinsightsinto pages 6-7, masai2025novelinsightsinto pages 12-13, masai2025novelinsightsinto pages 1-1, shkrigunov2023theapplicationof pages 8-9)
Subcellular localization	In human testis, hCRISP2 localizes to nuclei of primary spermatocytes, round spermatids, and early elongated spermatids; later also to cytoplasm, flagellum, and equatorial segment. In ejaculated sperm, signal is reported in cytoplasmic droplet, flagellum, equatorial segment, and basal head/connecting-piece regions. Evidence comes from immunofluorescence/confocal z-stacks, antibody controls, western blotting, immunoprecipitation, and MS.	Primary	(masai2025novelinsightsinto pages 6-7, masai2025novelinsightsinto pages 8-9, masai2025novelinsightsinto pages 12-13, masai2025novelinsightsinto pages 1-1, masai2025novelinsightsinto pages 7-8, masai2025novelinsightsinto pages 5-6)
Molecular mechanisms	Current understanding supports CRISP2 as a structural/functional sperm protein rather than an enzyme. Review-level evidence places CRISP2 in Ca2+ signaling via regulation of ryanodine receptor-mediated Ca2+ flux and more broadly in ion-channel modulation relevant to motility, capacitation, and acrosome reaction. A 2024 JBC study also shows CRISP2 can bind sterol and mediate sterol export, adding a biochemical activity within the CAP domain framework.	Review + primary	(gibbs2008thecapsuperfamily pages 17-17, gibbs2008thecapsuperfamily pages 18-19, atab2024alpha1bglycoprotein(a1bg) pages 1-2, atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 9-11)
Binding partners/regulators	CRISP2 is reported in sperm protein complexes and has literature-supported interactions with MAP3K11/MLK3 and GGN1; human sperm IP-MS recovered CRISP2 with co-detected proteins including ACR and ACRBP. In 2024, A1BG was shown to bind CRISP2 with high affinity and inhibit its sterol-binding/export activity; interaction requires Mg2+ and maps mainly to A1BG Ig3.	Primary + review + proteomics	(masai2025novelinsightsinto pages 38-40, gibbs2008thecapsuperfamily pages 17-17, atab2024alpha1bglycoprotein(a1bg) pages 1-2, atab2024alpha1bglycoprotein(a1bg) pages 11-12, atab2024alpha1bglycoprotein(a1bg) pages 5-7)
Disease/phenotype links	The strongest human disease link is male infertility, especially sperm motility-related phenotypes. Recent review summaries cite miR-27b/miR-27b-3p and miR-509-5p as CRISP2-related regulators in azoospermia/NOA or asthenozoospermia contexts; higher miR-27b is associated with impaired sperm morphology/progressive motility and inverse association with CRISP2 protein. Open Targets currently lists only weak target–disease association evidence for CRISP2 in male infertility.	Review + database	(shi2024micrornasinspermatogenesis pages 9-10, shi2024micrornasinspermatogenesis pages 3-4, shi2024micrornasinspermatogenesis pages 4-5, shi2024micrornasinspermatogenesis pages 19-20, OpenTargets Search: male infertility,asthenozoospermia,azoospermia,infertility-CRISP2)
Applications/biomarkers	CRISP2 is already used in sperm/ejaculate proteomics panels as a testis-specific or fertility-relevant protein and is discussed as a candidate biomarker for male infertility screening, though direct clinical implementation remains limited. Its localization and sperm-specificity also keep it of interest as a prospective fertility or contraceptive target.	Proteomics + review	(shkrigunov2023theapplicationof pages 8-9, atab2024alpha1bglycoprotein(a1bg) pages 1-2)
Key quantitative data	Human ejaculate proteomics (2023) reported CRISP2 validated unique peptides: ejaculate 11, seminal plasma 30, spermatozoa 8; NSAF values 0.49, 0.383, and 0.474, respectively. In 2024 biochemical studies, A1BG bound CRISP2 with Kd about 13.72 ± 2.5 nM (also ~10.3 ± 2.4 nM under Mg2+ conditions), Ig3 bound with Kd about 13.8 ± 1.14 nM, and A1BG coexpression inhibited CRISP2/Pry-family sterol secretion by >50%; CRISP2 bound cholesterol sulfate with reported Kd values in low micromolar to nanomolar/Mg2+-dependent assay ranges depending on assay conditions.	Proteomics + primary	(shkrigunov2023theapplicationof pages 8-9, atab2024alpha1bglycoprotein(a1bg) pages 11-12, atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 5-7, atab2024alpha1bglycoprotein(a1bg) pages 12-13)

Table: This table summarizes the current evidence-based functional annotation of human CRISP2 (UniProt P16562), including identity, localization, mechanisms, fertility links, and quantitative findings. It emphasizes recent 2023-2024 data where available while anchoring claims to authoritative reviews and primary studies.

9) Conclusions and research gaps

Primary biological role: The strongest supported functional annotation for human CRISP2 is as a sperm-associated CAP/CRISP family protein involved in spermatogenesis and sperm functional competence, with roles tied to sperm structure (flagellum/connecting piece) and fertilization interfaces (EqS) (masai2025novelinsightsinto pages 1-1, gibbs2008thecapsuperfamily pages 17-17).
Mechanistic hypotheses with mixed maturity: Ion-channel/Ca2+ regulatory roles are strongly embedded in review consensus and appear in proteomics functional annotation, but direct, human-specific mechanistic studies remain relatively sparse in the retrieved set (gibbs2008thecapsuperfamily pages 18-19, shkrigunov2023theapplicationof pages 8-9).
Notable 2024 mechanistic advance: Sterol-binding/export activity and regulation by A1BG provides a concrete biochemical mechanism and quantified interaction parameters that can inform future reproductive physiology studies (atab2024alpha1bglycoprotein(a1bg) pages 2-4, atab2024alpha1bglycoprotein(a1bg) pages 12-13).
Clinical translation: CRISP2 is measurable and present in proteomics workflows used for infertility research; however, robust clinical test development will require targeted assay validation and clear phenotype-linked performance metrics (as emphasized by expert review) (parkes2024bringingproteomicsto pages 28-29, parkes2024bringingproteomicsto pages 6-7).

Key source URLs (with publication dates)

Endocrine Reviews (Dec 2008): https://doi.org/10.1210/er.2008-0032 (gibbs2008thecapsuperfamily pages 1-2)
Int. J. Dev. Biol. (2008): https://doi.org/10.1387/ijdb.072545lb (burnett2008crispproteinsand pages 1-2)
Biomedicines (Dec 2023): https://doi.org/10.3390/biomedicines12010049 (shkrigunov2023theapplicationof pages 8-9)
Frontiers in Endocrinology (Feb 2024): https://doi.org/10.3389/fendo.2024.1293368 (shi2024micrornasinspermatogenesis pages 3-4)
Expert Review of Proteomics (Apr 2024): https://doi.org/10.1080/14789450.2024.2327553 (parkes2024bringingproteomicsto pages 29-31)
Frontiers in Endocrinology (Apr 2024): https://doi.org/10.3389/fendo.2024.1327800 (fietz2024proteomicbiomarkersin pages 1-2)
J. Biol. Chem. (Dec 2024): https://doi.org/10.1016/j.jbc.2024.107910 (atab2024alpha1bglycoprotein(a1bg) pages 2-4)
Biology of Reproduction (Mar 2025; human localization/biochemistry): https://doi.org/10.1093/biolre/ioaf051 (masai2025novelinsightsinto pages 1-1)

References

(masai2025novelinsightsinto pages 11-11): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 14-15): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 38-40): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(gibbs2008thecapsuperfamily pages 4-4): Gerard M. Gibbs, Kim Roelants, and Moira K. O'Bryan. The cap superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins—roles in reproduction, cancer, and immune defense. Endocrine Reviews, 29:865-897, Dec 2008. URL: https://doi.org/10.1210/er.2008-0032, doi:10.1210/er.2008-0032. This article has 615 citations and is from a domain leading peer-reviewed journal.
(gibbs2008thecapsuperfamily pages 3-4): Gerard M. Gibbs, Kim Roelants, and Moira K. O'Bryan. The cap superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins—roles in reproduction, cancer, and immune defense. Endocrine Reviews, 29:865-897, Dec 2008. URL: https://doi.org/10.1210/er.2008-0032, doi:10.1210/er.2008-0032. This article has 615 citations and is from a domain leading peer-reviewed journal.
(gibbs2008thecapsuperfamily pages 4-5): Gerard M. Gibbs, Kim Roelants, and Moira K. O'Bryan. The cap superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins—roles in reproduction, cancer, and immune defense. Endocrine Reviews, 29:865-897, Dec 2008. URL: https://doi.org/10.1210/er.2008-0032, doi:10.1210/er.2008-0032. This article has 615 citations and is from a domain leading peer-reviewed journal.
(gibbs2008thecapsuperfamily pages 17-17): Gerard M. Gibbs, Kim Roelants, and Moira K. O'Bryan. The cap superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins—roles in reproduction, cancer, and immune defense. Endocrine Reviews, 29:865-897, Dec 2008. URL: https://doi.org/10.1210/er.2008-0032, doi:10.1210/er.2008-0032. This article has 615 citations and is from a domain leading peer-reviewed journal.
(gibbs2008thecapsuperfamily pages 18-19): Gerard M. Gibbs, Kim Roelants, and Moira K. O'Bryan. The cap superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins—roles in reproduction, cancer, and immune defense. Endocrine Reviews, 29:865-897, Dec 2008. URL: https://doi.org/10.1210/er.2008-0032, doi:10.1210/er.2008-0032. This article has 615 citations and is from a domain leading peer-reviewed journal.
(masai2025novelinsightsinto pages 1-1): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 6-7): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 7-8): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 5-6): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(shkrigunov2023theapplicationof pages 8-9): Timur Shkrigunov, Victor Zgoda, Peter Klimenko, Anna Kozlova, Maria Klimenko, Andrey Lisitsa, Mark Kurtser, and Natalia Petushkova. The application of ejaculate-based shotgun proteomics for male infertility screening. Biomedicines, 12:49, Dec 2023. URL: https://doi.org/10.3390/biomedicines12010049, doi:10.3390/biomedicines12010049. This article has 2 citations.
(atab2024alpha1bglycoprotein(a1bg) pages 2-4): Ola El Atab, Barkha Gupta, Zhu Han, Jiri Stribny, Oluwatoyin A. Asojo, and Roger Schneiter. Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2. Journal of Biological Chemistry, 300:107910, Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107910, doi:10.1016/j.jbc.2024.107910. This article has 4 citations and is from a domain leading peer-reviewed journal.
(atab2024alpha1bglycoprotein(a1bg) pages 12-13): Ola El Atab, Barkha Gupta, Zhu Han, Jiri Stribny, Oluwatoyin A. Asojo, and Roger Schneiter. Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2. Journal of Biological Chemistry, 300:107910, Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107910, doi:10.1016/j.jbc.2024.107910. This article has 4 citations and is from a domain leading peer-reviewed journal.
(atab2024alpha1bglycoprotein(a1bg) pages 1-2): Ola El Atab, Barkha Gupta, Zhu Han, Jiri Stribny, Oluwatoyin A. Asojo, and Roger Schneiter. Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2. Journal of Biological Chemistry, 300:107910, Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107910, doi:10.1016/j.jbc.2024.107910. This article has 4 citations and is from a domain leading peer-reviewed journal.
(atab2024alpha1bglycoprotein(a1bg) pages 9-11): Ola El Atab, Barkha Gupta, Zhu Han, Jiri Stribny, Oluwatoyin A. Asojo, and Roger Schneiter. Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2. Journal of Biological Chemistry, 300:107910, Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107910, doi:10.1016/j.jbc.2024.107910. This article has 4 citations and is from a domain leading peer-reviewed journal.
(atab2024alpha1bglycoprotein(a1bg) pages 11-12): Ola El Atab, Barkha Gupta, Zhu Han, Jiri Stribny, Oluwatoyin A. Asojo, and Roger Schneiter. Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2. Journal of Biological Chemistry, 300:107910, Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107910, doi:10.1016/j.jbc.2024.107910. This article has 4 citations and is from a domain leading peer-reviewed journal.
(shkrigunov2023theapplicationof media 5dc187ee): Timur Shkrigunov, Victor Zgoda, Peter Klimenko, Anna Kozlova, Maria Klimenko, Andrey Lisitsa, Mark Kurtser, and Natalia Petushkova. The application of ejaculate-based shotgun proteomics for male infertility screening. Biomedicines, 12:49, Dec 2023. URL: https://doi.org/10.3390/biomedicines12010049, doi:10.3390/biomedicines12010049. This article has 2 citations.
(shi2024micrornasinspermatogenesis pages 3-4): Ziyan Shi, Miao Yu, Tingchao Guo, Yu Sui, Zhiying Tian, Xiang Ni, Xinren Chen, Miao Jiang, Jingyi Jiang, Yongping Lu, and Meina Lin. Micrornas in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers. Frontiers in Endocrinology, Feb 2024. URL: https://doi.org/10.3389/fendo.2024.1293368, doi:10.3389/fendo.2024.1293368. This article has 56 citations.
(shi2024micrornasinspermatogenesis pages 4-5): Ziyan Shi, Miao Yu, Tingchao Guo, Yu Sui, Zhiying Tian, Xiang Ni, Xinren Chen, Miao Jiang, Jingyi Jiang, Yongping Lu, and Meina Lin. Micrornas in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers. Frontiers in Endocrinology, Feb 2024. URL: https://doi.org/10.3389/fendo.2024.1293368, doi:10.3389/fendo.2024.1293368. This article has 56 citations.
(shi2024micrornasinspermatogenesis pages 19-20): Ziyan Shi, Miao Yu, Tingchao Guo, Yu Sui, Zhiying Tian, Xiang Ni, Xinren Chen, Miao Jiang, Jingyi Jiang, Yongping Lu, and Meina Lin. Micrornas in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers. Frontiers in Endocrinology, Feb 2024. URL: https://doi.org/10.3389/fendo.2024.1293368, doi:10.3389/fendo.2024.1293368. This article has 56 citations.
(fietz2024proteomicbiomarkersin pages 2-3): Daniela Fietz, Raouda Sgaier, Liza O’Donnell, Peter G. Stanton, Laura F. Dagley, Andrew I. Webb, Hans-Christian Schuppe, Thorsten Diemer, and Adrian Pilatz. Proteomic biomarkers in seminal plasma as predictors of reproductive potential in azoospermic men. Frontiers in Endocrinology, Apr 2024. URL: https://doi.org/10.3389/fendo.2024.1327800, doi:10.3389/fendo.2024.1327800. This article has 17 citations.
(fietz2024proteomicbiomarkersin pages 1-2): Daniela Fietz, Raouda Sgaier, Liza O’Donnell, Peter G. Stanton, Laura F. Dagley, Andrew I. Webb, Hans-Christian Schuppe, Thorsten Diemer, and Adrian Pilatz. Proteomic biomarkers in seminal plasma as predictors of reproductive potential in azoospermic men. Frontiers in Endocrinology, Apr 2024. URL: https://doi.org/10.3389/fendo.2024.1327800, doi:10.3389/fendo.2024.1327800. This article has 17 citations.
(fietz2024proteomicbiomarkersin pages 12-12): Daniela Fietz, Raouda Sgaier, Liza O’Donnell, Peter G. Stanton, Laura F. Dagley, Andrew I. Webb, Hans-Christian Schuppe, Thorsten Diemer, and Adrian Pilatz. Proteomic biomarkers in seminal plasma as predictors of reproductive potential in azoospermic men. Frontiers in Endocrinology, Apr 2024. URL: https://doi.org/10.3389/fendo.2024.1327800, doi:10.3389/fendo.2024.1327800. This article has 17 citations.
(parkes2024bringingproteomicsto pages 28-29): Rachel Parkes and Thomas X. Garcia. Bringing proteomics to bear on male fertility: key lessons. Expert Review of Proteomics, 21:181-203, Apr 2024. URL: https://doi.org/10.1080/14789450.2024.2327553, doi:10.1080/14789450.2024.2327553. This article has 7 citations and is from a peer-reviewed journal.
(parkes2024bringingproteomicsto pages 6-7): Rachel Parkes and Thomas X. Garcia. Bringing proteomics to bear on male fertility: key lessons. Expert Review of Proteomics, 21:181-203, Apr 2024. URL: https://doi.org/10.1080/14789450.2024.2327553, doi:10.1080/14789450.2024.2327553. This article has 7 citations and is from a peer-reviewed journal.
(parkes2024bringingproteomicsto pages 29-31): Rachel Parkes and Thomas X. Garcia. Bringing proteomics to bear on male fertility: key lessons. Expert Review of Proteomics, 21:181-203, Apr 2024. URL: https://doi.org/10.1080/14789450.2024.2327553, doi:10.1080/14789450.2024.2327553. This article has 7 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 11-12): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 12-13): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(masai2025novelinsightsinto pages 8-9): Thibault Masai, Amandine Delnatte, Marie Dendievel, Denis Nonclercq, Annica Frau, Jean-François Simon, Vanessa Arcolia, Ruddy Wattiez, Baptiste Leroy, Patricia S Cuasnicu, Pascale Lybaert, and Elise Hennebert. Novel insights into human crisp2: localization in reproductive tissues and sperm, and molecular characterization. Biology of reproduction, 112:1167-1184, Mar 2025. URL: https://doi.org/10.1093/biolre/ioaf051, doi:10.1093/biolre/ioaf051. This article has 1 citations and is from a peer-reviewed journal.
(atab2024alpha1bglycoprotein(a1bg) pages 5-7): Ola El Atab, Barkha Gupta, Zhu Han, Jiri Stribny, Oluwatoyin A. Asojo, and Roger Schneiter. Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export by crisp2. Journal of Biological Chemistry, 300:107910, Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107910, doi:10.1016/j.jbc.2024.107910. This article has 4 citations and is from a domain leading peer-reviewed journal.
(shi2024micrornasinspermatogenesis pages 9-10): Ziyan Shi, Miao Yu, Tingchao Guo, Yu Sui, Zhiying Tian, Xiang Ni, Xinren Chen, Miao Jiang, Jingyi Jiang, Yongping Lu, and Meina Lin. Micrornas in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers. Frontiers in Endocrinology, Feb 2024. URL: https://doi.org/10.3389/fendo.2024.1293368, doi:10.3389/fendo.2024.1293368. This article has 56 citations.
(OpenTargets Search: male infertility,asthenozoospermia,azoospermia,infertility-CRISP2): Open Targets Query (male infertility,asthenozoospermia,azoospermia,infertility-CRISP2, 1 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.
(gibbs2008thecapsuperfamily pages 1-2): Gerard M. Gibbs, Kim Roelants, and Moira K. O'Bryan. The cap superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins—roles in reproduction, cancer, and immune defense. Endocrine Reviews, 29:865-897, Dec 2008. URL: https://doi.org/10.1210/er.2008-0032, doi:10.1210/er.2008-0032. This article has 615 citations and is from a domain leading peer-reviewed journal.
(burnett2008crispproteinsand pages 1-2): Lindsey A. Burnett, Xueyu Xiang, Allan L. Bieber, and Douglas E. Chandler. Crisp proteins and sperm chemotaxis: discovery in amphibians and explorations in mammals. The International journal of developmental biology, 52 5-6:489-501, Jan 2008. URL: https://doi.org/10.1387/ijdb.072545lb, doi:10.1387/ijdb.072545lb. This article has 27 citations.

Artifacts

Edison artifact artifact-00

Citations

masai2025novelinsightsinto pages 38-40
gibbs2008thecapsuperfamily pages 3-4
gibbs2008thecapsuperfamily pages 4-5
gibbs2008thecapsuperfamily pages 17-17
masai2025novelinsightsinto pages 1-1
masai2025novelinsightsinto pages 5-6
shkrigunov2023theapplicationof pages 8-9
shi2024micrornasinspermatogenesis pages 3-4
shi2024micrornasinspermatogenesis pages 4-5
fietz2024proteomicbiomarkersin pages 12-12
parkes2024bringingproteomicsto pages 29-31
gibbs2008thecapsuperfamily pages 1-2
burnett2008crispproteinsand pages 1-2
fietz2024proteomicbiomarkersin pages 1-2
masai2025novelinsightsinto pages 11-11
masai2025novelinsightsinto pages 14-15
gibbs2008thecapsuperfamily pages 4-4
gibbs2008thecapsuperfamily pages 18-19
masai2025novelinsightsinto pages 6-7
masai2025novelinsightsinto pages 7-8
shi2024micrornasinspermatogenesis pages 19-20
fietz2024proteomicbiomarkersin pages 2-3
parkes2024bringingproteomicsto pages 28-29
parkes2024bringingproteomicsto pages 6-7
masai2025novelinsightsinto pages 11-12
masai2025novelinsightsinto pages 12-13
masai2025novelinsightsinto pages 8-9
shi2024micrornasinspermatogenesis pages 9-10
https://doi.org/10.1210/er.2008-0032
https://doi.org/10.1387/ijdb.072545lb
https://doi.org/10.3390/biomedicines12010049
https://doi.org/10.3389/fendo.2024.1293368
https://doi.org/10.1080/14789450.2024.2327553
https://doi.org/10.3389/fendo.2024.1327800
https://doi.org/10.1016/j.jbc.2024.107910
https://doi.org/10.1093/biolre/ioaf051
https://doi.org/10.1093/biolre/ioaf051,
https://doi.org/10.1210/er.2008-0032,
https://doi.org/10.3390/biomedicines12010049,
https://doi.org/10.1016/j.jbc.2024.107910,
https://doi.org/10.3389/fendo.2024.1293368,
https://doi.org/10.3389/fendo.2024.1327800,
https://doi.org/10.1080/14789450.2024.2327553,
https://doi.org/10.1387/ijdb.072545lb,

Perplexity

(CRISP2-deep-research-perplexity-lite.md)

**Key Concepts and Definitions** Perplexity sonar-pro 13 citations 2025-11-15T18:33:52.027795

The CRISP2 (Cysteine-Rich Secretory Protein 2) gene encodes a protein primarily involved in male reproductive biology, with key roles in sperm function, ion channel regulation, and potential disease associations, particularly male infertility.

Key Concepts and Definitions

CRISP2 is a member of the cysteine-rich secretory protein (CRISP) family, predominantly expressed in the testis and incorporated into developing sperm[2][3][6][7][13].
The protein is also known as TPX-1 and is highly enriched in haploid germ cells, localizing mainly to the acrosome and flagellum of sperm[2][6][7].

Molecular Function

Ion Channel Regulation: CRISP2 is predicted to regulate the activity of certain ion channels, particularly those involved in calcium fluxes during sperm capacitation, a process essential for fertilization[3][13].
Gamete Fusion: It facilitates gamete fusion by binding to complementary sites on the egg surface and modulates calcium ion flux through interactions with ryanodine receptors and ion channels such as CATSPER1[2][7].
Mucus Rheology: In non-reproductive tissues, CRISP2 may modulate mucus properties in the airways, though this function is less characterized in humans[9].

Biological Processes

Spermatogenesis: CRISP2 is critical for sperm development and maturation[6][7].
Sperm Motility: It modulates flagellar motility, which is essential for sperm movement[7].
Acrosome Reaction: CRISP2 is involved in the acrosome reaction, a key step in fertilization where the sperm releases enzymes to penetrate the egg[7].
Cell Proliferation and Apoptosis: Recent studies suggest roles in cell proliferation, apoptosis, and extracellular matrix maintenance, particularly in the context of intervertebral disc integrity[4].

Cellular Localization

Acrosome and Flagellum: CRISP2 is primarily localized to the acrosome and flagellum of sperm cells[2][6][7].
Extracellular Region: It is predicted to be active in the extracellular space, consistent with its secretory nature[2][3][12].
Other Tissues: While testis expression is dominant, low-level expression has been detected in other tissues, including the airways and possibly the intervertebral disc[4][9].

Protein Domains

CAP Domain: CRISP2 contains a CAP (Cysteine-rich secretory protein, Antigen 5, and Pathogenesis-related 1 protein) domain, which is characteristic of the CRISP family and is involved in protein-protein interactions and ion channel modulation[2][13].
Cysteine-Rich Region: The protein is rich in cysteine residues, which form disulfide bonds critical for its structure and function[2][13].

Known Interactions

Ion Channels: CRISP2 interacts with sperm-specific ion channels, including CATSPER1 and ryanodine receptors, influencing calcium signaling[2][3][13].
PSP94: It has been identified as a binding partner of PSP94 (Prostate Secretory Protein 94) in human sperm, suggesting a role in sperm maturation or function[11].
Oligomerization: CRISP2 can form oligomers in both the sperm head and tail, with different molecular weights and potential functional implications[8].

Disease Associations

Male Infertility: Mutations or dysregulation of CRISP2 are associated with male infertility, likely due to impaired sperm motility, capacitation, or fertilization ability[3][6][7].
Intervertebral Disc Degeneration (IDD): Recent research implicates CRISP2 in disc cell integrity, with dysregulation linked to disc degeneration. CRISP2 is being explored as a biomarker and therapeutic target for IDD[4].
Cancer Prognosis: Elevated CRISP2 expression has been correlated with patient survival in various cancers, though the mechanisms remain under investigation[4].

Recent Developments (2023–2024)

Therapeutic Targeting: Hesperidin, a natural compound, has been shown to reduce CRISP2 expression and protect against intervertebral disc degeneration, suggesting new therapeutic avenues[4].
Immune Modulation: CRISP2 expression correlates with immune cell infiltration in tumors, indicating a possible role in tumor microenvironment modulation[4].
Epigenetic Regulation: DNA methylation and histone modification profiles of CRISP2 are being mapped to understand its regulation in different tissues and disease states[2].

Expert Opinions and Analysis

CRISP2 is considered a critical sperm protein for male fertility, with its absence or dysfunction leading to significant reproductive issues[6][7].
Its emerging roles in non-reproductive tissues and diseases such as IDD and cancer highlight the need for further research into its broader biological significance[4].

Relevant Statistics and Data

Expression: CRISP2 is one of the most highly expressed proteins in human testis, with much lower expression in other tissues[2][5].
Functional Associations: Over 2,600 functional associations have been identified for CRISP2 across various biological categories, underscoring its pleiotropic roles[2].

References (with URLs and Dates)

Citations

https://geneglobe.qiagen.com/us/knowledge/gene/ENSG00000124490
https://maayanlab.cloud/Harmonizome/gene/CRISP2
https://www.genecards.org/cgi-bin/carddisp.pl?gene=CRISP2
https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1447152/full
https://www.proteinatlas.org/ENSG00000124490-CRISP2
https://pubmed.ncbi.nlm.nih.gov/40079119/
https://academic.oup.com/biolreprod/article/92/1/28,%201-9/2434071
https://bioone.org/journals/biology-of-reproduction/volume-105/issue-5/ioab145/Characterization-of-different-oligomeric-forms-of-CRISP2-in-the-perinuclear/10.1093/biolre/ioab145.full
https://genular.atomic-lab.org/details-gene/7180?contexts%5B0%5D=UBERON0001898_PATO0000461
https://en.wikipedia.org/wiki/CRISP2
https://www.ncbi.nlm.nih.gov/gene?Db=gene&Cmd=DetailsSearch&Term=7180
https://www.ncbi.nlm.nih.gov/gene/7180
https://www.uniprot.org/uniprotkb/P16562/entry

📄 View Raw YAML

id: P16562
gene_symbol: CRISP2
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: Cysteine-rich secretory protein 2 (CRISP2) is a testis-specific
  secretory protein that plays critical roles in male reproductive biology. It
  is incorporated into developing sperm during spermatogenesis and localizes
  primarily to the acrosome (particularly the equatorial segment), flagellum,
  and cytoplasmic droplet of mature sperm. CRISP2 functions as an ion channel
  regulator, particularly modulating calcium flux during sperm capacitation
  (including ryanodine receptor-mediated Ca2+ release), and is involved in the
  acrosome reaction and fertilization processes. The protein contains
  characteristic CAP and cysteine-rich (ShKT/CRISP) domains that mediate
  protein-protein interactions and ion channel regulation; recent biochemical
  evidence shows the CAP domain also binds sterols (e.g., cholesterol sulfate)
  and mediates sterol export, an activity inhibited by A1BG binding.
existing_annotations:
- term:
    id: GO:0005615
    label: extracellular space
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: CRISP2 is a secretory protein that is released into extracellular
      space. The IBA annotation is based on phylogenetic inference across the
      CRISP family, which are characterized as secreted proteins.
    action: ACCEPT
    reason: The annotation is correct and well-supported. CRISP2 contains a
      signal peptide (residues 1-21) and is annotated as "Secreted" in UniProt.
      The deep research confirms CRISP2 "is predicted to be active in the
      extracellular space, consistent with its secretory nature" and localizes
      to the acrosome and flagellum of sperm cells, which are extracellular
      compartments. The IBA evidence provides strong phylogenetic support across
      orthologous CRISP family members.
    proposed_replacement_terms: []
    additional_reference_ids:
    - PMID:8665901
    supported_by:
    - reference_id: PMID:8665901
      supporting_text: "CRISP-2/TPX1 transcripts are...detected mainly in the testis
        and also in the epididymis"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is primarily localized to the acrosome and flagellum
        of sperm cells. It is predicted to be active in the extracellular space, consistent
        with its secretory nature"
    - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Secreted"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "In ejaculated sperm, CRISP2 is reported in the **cytoplasmic
        droplet**, **flagellum**, and **EqS**, consistent with roles in motility and
        gamete fusion"
- term:
    id: GO:0005576
    label: extracellular region
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: This is a broad extracellular localization term assigned by
      automated evidence based on InterPro domain signatures and UniProt
      subcellular location annotation.
    action: ACCEPT
    reason: The annotation is correct as CRISP2 is a secreted protein found in
      extracellular regions. While GO:0005615 (extracellular space) is more
      specific, GO:0005576 (extracellular region) is also accurate and
      represents a valid parent term. The IEA annotation is appropriately
      conservative, providing broad localization information based on sequence
      features and subcellular location keywords. Having both the specific term
      (GO:0005615) and broader term (GO:0005576) is acceptable and provides
      complete annotation coverage.
    proposed_replacement_terms: []
    additional_reference_ids:
    - PMID:8665901
    supported_by:
    - reference_id: GO_REF:0000120
      supporting_text: "Combined Automated Annotation using Multiple IEA Methods based
        on InterPro:IPR018244 and UniProtKB-SubCell:SL-0243"
    - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Secreted"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "CRISPs as typically **two-domain proteins** comprising an N-terminal
        **CAP domain** plus a C-terminal **cysteine-rich CRISP domain**"
- term:
    id: GO:0005615
    label: extracellular space
  evidence_type: TAS
  original_reference_id: PMID:8665901
  review:
    summary: This annotation is supported by the foundational characterization
      paper for the human CRISP family by Kraetzschmar et al. 1996, which
      described CRISP2 tissue distribution and confirmed it as a secreted
      protein.
    action: ACCEPT
    reason: The TAS (Traceable Author Statement) annotation is well-founded.
      PMID:8665901 is the seminal paper characterizing CRISP2 (referred to as
      TPX1 in that work) as a secretory protein with testis and epididymis
      expression. The paper states "CRISP-2 cDNA corresponds to the previously
      described TPX1 form" and describes tissue distribution indicating
      secretory nature. While the abstract does not explicitly state
      "extracellular space," the characterization of CRISP proteins as secretory
      proteins with cysteine-rich domains supports extracellular localization.
      This represents core literature-based evidence for CRISP2 localization.
    proposed_replacement_terms: []
    additional_reference_ids: []
    supported_by:
    - reference_id: PMID:8665901
      supporting_text: "CRISP-2/TPX1 transcripts are...detected mainly in the testis
        and also in the epididymis... We report the isolation and characterisation
        of cDNAs encoding three different, human members of the cysteine-rich secretory
        protein (CRISP) family."
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "In human epididymis, CRISP2 staining is observed in sperm within
        the lumen (including a dense spot at the basal head region and along the flagellum),
        while the epididymal epithelium is negative"
- term:
    id: GO:0005246
    label: calcium channel regulator activity
  evidence_type: NAS
  review:
    summary: Added to align core_functions with existing annotations.
    action: NEW
    reason: Core function term not present in existing_annotations.
    supported_by:
    - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
      supporting_text: "May regulate some ion channels' activity and thereby regulate
        calcium fluxes during sperm capacitation."
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is predicted to regulate the activity of certain ion
        channels, particularly those involved in calcium fluxes during sperm capacitation,
        a process essential for fertilization"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is involved in the acrosome reaction, a key step in
        fertilization where the sperm releases enzymes to penetrate the egg"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is primarily localized to the acrosome and flagellum
        of sperm cells"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "Review-level synthesis places CRISP2 in sperm Ca2+ signaling
        through **ryanodine receptor (RyR)-mediated Ca2+ release** and broader ion-channel
        modulation"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "A 2023 ejaculate-based shotgun proteomics study explicitly
        annotates CRISP2 as potentially regulating **ion channels** and thereby **calcium
        fluxes during sperm capacitation**"
- term:
    id: GO:0001669
    label: acrosomal vesicle
  evidence_type: NAS
  review:
    summary: Added to align core_functions with existing annotations.
    action: NEW
    reason: Core function term not present in existing_annotations.
    supported_by:
    - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
      supporting_text: "May regulate some ion channels' activity and thereby regulate
        calcium fluxes during sperm capacitation."
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is predicted to regulate the activity of certain ion
        channels, particularly those involved in calcium fluxes during sperm capacitation,
        a process essential for fertilization"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is involved in the acrosome reaction, a key step in
        fertilization where the sperm releases enzymes to penetrate the egg"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is primarily localized to the acrosome and flagellum
        of sperm cells"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "Late elongated spermatids:** CRISP2 also seen in the **flagellum**
        and the **equatorial segment (EqS)** of the acrosome"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "In ejaculated sperm, CRISP2 is reported in the **cytoplasmic
        droplet**, **flagellum**, and **EqS**, consistent with roles in motility and
        gamete fusion"
- term:
    id: GO:0048240
    label: sperm capacitation
  evidence_type: NAS
  review:
    summary: Added to align core_functions with existing annotations.
    action: NEW
    reason: Core function term not present in existing_annotations.
    supported_by:
    - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
      supporting_text: "May regulate some ion channels' activity and thereby regulate
        calcium fluxes during sperm capacitation."
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is predicted to regulate the activity of certain ion
        channels, particularly those involved in calcium fluxes during sperm capacitation,
        a process essential for fertilization"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is involved in the acrosome reaction, a key step in
        fertilization where the sperm releases enzymes to penetrate the egg"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is primarily localized to the acrosome and flagellum
        of sperm cells"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "A 2023 ejaculate-based shotgun proteomics study explicitly
        annotates CRISP2 as potentially regulating **ion channels** and thereby **calcium
        fluxes during sperm capacitation**"
- term:
    id: GO:0007340
    label: acrosome reaction
  evidence_type: NAS
  review:
    summary: Added to align core_functions with existing annotations.
    action: NEW
    reason: Core function term not present in existing_annotations.
    supported_by:
    - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
      supporting_text: "May regulate some ion channels' activity and thereby regulate
        calcium fluxes during sperm capacitation."
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is predicted to regulate the activity of certain ion
        channels, particularly those involved in calcium fluxes during sperm capacitation,
        a process essential for fertilization"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is involved in the acrosome reaction, a key step in
        fertilization where the sperm releases enzymes to penetrate the egg"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
      supporting_text: "CRISP2 is primarily localized to the acrosome and flagellum
        of sperm cells"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "Late elongated spermatids:** CRISP2 also seen in the **flagellum**
        and the **equatorial segment (EqS)** of the acrosome"
- term:
    id: GO:0032934
    label: sterol binding
  evidence_type: NAS
  review:
    summary: Added based on 2024 biochemical evidence that the CRISP2 CAP domain binds
      cholesterol sulfate and mediates sterol export in a yeast assay; activity is
      inhibited by A1BG binding in a Mg2+-dependent manner.
    action: NEW
    reason: Novel mechanistic activity supported by PMID:39433128 (El Atab et al.
      2024, J Biol Chem) demonstrating direct sterol binding via the CAP domain. This
      activity is not in current GOA but represents a credible biochemical function
      from a domain-leading peer-reviewed journal.
    supported_by:
    - reference_id: PMID:39433128
      supporting_text: "Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and
        export by crisp2"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "biochemical evidence that CRISP2 participates in **sterol
        binding and sterol export** in a yeast-based functional model and that this
        activity can be strongly regulated by A1BG"
    - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
      supporting_text: "Coexpression of A1BG with CRISP2 (or related CAP proteins)
        reduced sterol secretion by **>50%** in vivo (yeast export assay)"
core_functions:
- description: Regulating calcium channel activity in the extracellular region to
    control calcium flux during sperm capacitation and the acrosome reaction
  supported_by:
  - reference_id: file:human/CRISP2/CRISP2-uniprot.txt
    supporting_text: "May regulate some ion channels' activity and thereby regulate
      calcium fluxes during sperm capacitation."
  - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
    supporting_text: "CRISP2 is predicted to regulate the activity of certain ion
      channels, particularly those involved in calcium fluxes during sperm capacitation,
      a process essential for fertilization"
  - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
    supporting_text: "CRISP2 is involved in the acrosome reaction, a key step in fertilization
      where the sperm releases enzymes to penetrate the egg"
  - reference_id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
    supporting_text: "CRISP2 is primarily localized to the acrosome and flagellum
      of sperm cells"
  - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
    supporting_text: "Review-level synthesis places CRISP2 in sperm Ca2+ signaling
      through **ryanodine receptor (RyR)-mediated Ca2+ release** and broader ion-channel
      modulation"
  molecular_function:
    id: GO:0005246
    label: calcium channel regulator activity
  directly_involved_in:
  - id: GO:0048240
    label: sperm capacitation
  - id: GO:0007340
    label: acrosome reaction
  locations:
  - id: GO:0005576
    label: extracellular region
  - id: GO:0001669
    label: acrosomal vesicle
  anatomical_locations:
  - id: UBERON:0000473
    label: testis
- description: Binding sterols (including cholesterol sulfate) via the CAP domain
    and mediating sterol export; this activity is inhibited by A1BG binding in a Mg2+-dependent
    manner. This biochemical activity was demonstrated heterologously in a yeast sterol-export
    model and provides a mechanistic basis for CRISP2 in lipid handling within reproductive
    tract fluids and sperm membranes.
  supported_by:
  - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
    supporting_text: "biochemical evidence that CRISP2 participates in **sterol binding
      and sterol export** in a yeast-based functional model and that this activity
      can be strongly regulated by A1BG"
  - reference_id: file:human/CRISP2/CRISP2-deep-research-falcon.md
    supporting_text: "Coexpression of A1BG with CRISP2 (or related CAP proteins) reduced
      sterol secretion by **>50%** in vivo (yeast export assay)"
  - reference_id: PMID:39433128
    supporting_text: "Alpha-1-b glycoprotein (a1bg) inhibits sterol-binding and export
      by crisp2"
  molecular_function:
    id: GO:0032934
    label: sterol binding
  locations:
  - id: GO:0005576
    label: extracellular region
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings:
  - statement: Phylogenetic inference supporting CRISP2 localization to
      extracellular space based on orthologous CRISP family members
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods.
  findings:
  - statement: Automated annotation based on InterPro domain signatures
      (IPR018244) and UniProt subcellular location keyword (SL-0243) supporting
      secreted/extracellular localization
- id: PMID:8665901
  title: The human cysteine-rich secretory protein (CRISP) family. Primary
    structure and tissue distribution of CRISP-1, CRISP-2 and CRISP-3.
  findings:
  - statement: First comprehensive characterization of human CRISP2 (TPX1)
      showing testis and epididymis-specific expression
    supporting_text: "CRISP-2/TPX1 transcripts are detected mainly in the testis and
      also in the epididymis"
  - statement: Established CRISP2 as member of cysteine-rich secretory protein
      family
    supporting_text: "We report the isolation and characterisation of cDNAs encoding
      three different, human members of the cysteine-rich secretory protein (CRISP)
      family... CRISP-2 cDNA corresponds to the previously described TPX1 form"
  - statement: Described tissue distribution patterns consistent with role in
      male reproduction
    supporting_text: "Northern blot analysis of various human organs indicates that
      CRISP-1 transcripts are epididymis-specific whereas CRISP-2/TPX1 transcripts
      are detected mainly in the testis and also in the epididymis"
- id: file:human/CRISP2/CRISP2-deep-research-perplexity-lite.md
  title: Deep research summary on CRISP2 gene function and biology
  findings:
  - statement: CRISP2 localizes to acrosome and flagellum of sperm cells
  - statement: Functions as ion channel regulator, particularly for calcium
      channels
  - statement: Critical for sperm capacitation, motility, and acrosome reaction
  - statement: Contains CAP domain involved in protein-protein interactions and
      ion channel modulation
  - statement: Associated with male infertility when dysregulated
- id: file:human/CRISP2/CRISP2-deep-research-falcon.md
  title: Falcon (Edison) deep research report on CRISP2 functional annotation
  findings:
  - statement: Human-specific 2025 study confirms CRISP2 localization to nuclei across
      spermatogenic stages and in flagellum/equatorial segment of late elongated spermatids
    supporting_text: "Late elongated spermatids:** CRISP2 also seen in the **flagellum**
      and the **equatorial segment (EqS)** of the acrosome"
  - statement: In ejaculated sperm CRISP2 is found in cytoplasmic droplet, flagellum,
      and equatorial segment
    supporting_text: "In ejaculated sperm, CRISP2 is reported in the **cytoplasmic
      droplet**, **flagellum**, and **EqS**, consistent with roles in motility and
      gamete fusion"
  - statement: CRISP2 regulates sperm Ca2+ signaling through ryanodine receptor-mediated
      Ca2+ release and broader ion-channel modulation
    supporting_text: "Review-level synthesis places CRISP2 in sperm Ca2+ signaling
      through **ryanodine receptor (RyR)-mediated Ca2+ release** and broader ion-channel
      modulation"
  - statement: Novel 2024 mechanistic advance — CRISP2 binds sterols (cholesterol
      sulfate) and mediates sterol export via the CAP domain; this is inhibited by
      A1BG binding (Kd ~13.7 nM, Mg2+-dependent)
    supporting_text: "biochemical evidence that CRISP2 participates in **sterol binding
      and sterol export** in a yeast-based functional model and that this activity
      can be strongly regulated by A1BG"
  - statement: CRISP2 protein levels are negatively associated with miR-27b expression,
      linking it to sperm motility/morphology phenotypes
    supporting_text: "high **miR-27b** expression is associated with reduced progressive
      motility and shows a **negative association with CRISP2 protein levels**"
  - statement: CRISP2 is integrated into sperm protein complexes with MAP3K11/MLK3
      and GGN1, and co-precipitates with ACR/ACRBP
    supporting_text: "review-level evidence reports CRISP2 binding partners including
      **MAP3K11/MLK3** (co-localizing in the acrosome) and **GGN1** (in the tail)"
- id: PMID:40079119
  title: "Novel insights into human CRISP2: localization in reproductive tissues and sperm, and molecular characterization†."
  findings:
  - statement: Direct human tissue immunolocalization showing CRISP2 in primary spermatocytes
      (faint nuclear puncta) through to late elongated spermatids (flagellum and equatorial
      segment)
  - statement: In epididymis, CRISP2 is detected in sperm within the lumen while the
      epididymal epithelium is negative
  - statement: IP-MS recovered CRISP2 with co-detected proteins including ACR and
      ACRBP, supporting participation in stable sperm complexes
- id: PMID:18824526
  title: "The CAP superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins--roles in reproduction, cancer, and immune defense."
  findings:
  - statement: Authoritative review defining CRISPs as two-domain CAP/CRD proteins
      with N-terminal CAP domain implicated in protein–protein/cell–cell interactions
      and C-terminal CRISP domain linked to ion-channel regulatory activity
  - statement: CRISP2 produced during spermatogenesis and localized to acrosome, accessory
      tail structures, and developing germ-cell membrane; binding partners include
      MAP3K11/MLK3 and GGN1
- id: PMID:18649262
  title: "Crisp proteins and sperm chemotaxis: discovery in amphibians and explorations in mammals."
  findings:
  - statement: Authoritative review of CRISP biology in amphibian and mammalian sperm
      function and chemotaxis
- id: PMID:39433128
  title: "Alpha-1-B glycoprotein (A1BG) inhibits sterol-binding and export by CRISP2."
  findings:
  - statement: Demonstrates that CRISP2 binds cholesterol sulfate and mediates sterol
      export in a yeast assay, and that A1BG binds CRISP2 with high affinity (Kd ~13.7
      nM, Mg2+-dependent) and inhibits sterol export by >50%
  - statement: Provides direct biochemical evidence that the CAP domain in CRISP2
      has sterol-binding activity inhibited by A1BG
- id: PMID:38255156
  title: "The Application of Ejaculate-Based Shotgun Proteomics for Male Infertility Screening."
  findings:
  - statement: Quantitative LC-MS/MS detection of CRISP2 (P16562) in ejaculate, seminal
      plasma, and spermatozoa, with functional annotation as ion-channel regulator
      affecting calcium fluxes during sperm capacitation
- id: PMID:38449855
  title: "MicroRNAs in spermatogenesis dysfunction and male infertility: clinical phenotypes, mechanisms and potential diagnostic biomarkers."
  findings:
  - statement: Reports that miR-27b targets CRISP2 and that high miR-27b is associated
      with reduced progressive sperm motility and a negative association with CRISP2
      protein levels
- id: PMID:38654926
  title: "Proteomic biomarkers in seminal plasma as predictors of reproductive potential in azoospermic men."
  findings:
  - statement: Clinical context for translation of testis-derived seminal plasma protein
      biomarkers (including CRISP family) for distinguishing obstructive vs non-obstructive
      azoospermia
- id: file:human/CRISP2/CRISP2-uniprot.txt
  title: UniProt entry for CRISP2 (P16562)
  findings:
  - statement: Contains signal peptide (residues 1-21) indicating secretory
      pathway
    supporting_text: "SIGNAL          1..21"
  - statement: Annotated as "Secreted" protein
    supporting_text: "SUBCELLULAR LOCATION: Secreted"
  - statement: Contains SCP domain (41-169) and ShKT domain (205-238)
    supporting_text: "DOMAIN          41..169 /note=\"SCP\" ... DOMAIN          205..238
      /note=\"ShKT\""
  - statement: Testis and epididymis-specific tissue expression
    supporting_text: "TISSUE SPECIFICITY: Testis and epididymis."
  - statement: May regulate ion channel activity and calcium fluxes during sperm
      capacitation
    supporting_text: "May regulate some ion channels' activity and thereby regulate
      calcium fluxes during sperm capacitation."

CRISP2

Gene Description

Existing Annotations Review

Core Functions

Regulating calcium channel activity in the extracellular region to control calcium flux during sperm capacitation and the acrosome reaction

References

Deep Research

Falcon

Research report: Human CRISP2 (UniProt P16562) functional annotation

0) Scope, identity verification, and ambiguity check

Target identity (verified)

Family/domain context

1) Key concepts and definitions (current understanding)

1.1 CAP superfamily and CRISP domain architecture

1.2 Functional framing of CRISP2

2) Expression and localization (where CRISP2 acts)

2.1 Tissue and cell-type specificity

2.2 Subcellular localization during human spermatogenesis

2.3 Localization in epididymis and ejaculated sperm

3) Molecular mechanism and pathways

3.1 Ion-channel/Ca2+ signaling links (conceptual and proteomics-supported)

3.2 Sterol binding/export activity and regulation by A1BG (2024 mechanistic advance)

3.3 Protein complexes and interaction landscape

4) Recent developments and latest research (prioritizing 2023–2024)

4.1 Quantitative detection of CRISP2 in human ejaculate/sperm proteomics (2023)

4.2 miRNA-linked regulation in infertility phenotypes (2024 synthesis)

4.3 Clinical context for biomarker translation (2024)

5) Current applications and real-world implementation

5.1 Male infertility screening panels (proteomics)

5.2 Seminal plasma proteomics for clinical decision support in azoospermia

6) Expert opinion and authoritative analysis (translation readiness)

7) Relevant statistics and quantitative data summary

8) Evidence-grounded summary table

9) Conclusions and research gaps

Key source URLs (with publication dates)

Artifacts

Citations

Perplexity

Citations

📄 View Raw YAML