Affinage

CATSPERZ

Cation channel sperm-associated auxiliary subunit zeta · UniProt Q9NTU4

Length
200 aa
Mass
22.8 kDa
Annotated
2026-06-09
6 papers in source corpus 2 papers cited in narrative 2 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 3/3 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CATSPERZ (encoded by Tex40, also C11orf20) is a subunit of the nine-subunit CatSper calcium channel complex of the sperm flagellum, where it organizes the channel's spatial architecture rather than forming the pore itself (PMID:28226241). Targeted disruption of CatSperζ reduces CatSper current and disrupts the linear quadrilateral nanodomain organization of the complex along the flagellum, leaving the proximal flagellum inflexible and altering the three-dimensional flagellar envelope (PMID:28226241). The consequence is severe male subfertility driven by impaired rheotaxis and in vivo sperm migration, establishing CATSPERZ as a structural organizer required to maintain CatSper nanodomain continuity and the flagellar mechanics needed for fertilization (PMID:28226241). Beyond this knockout characterization, no further mechanistic detail on CATSPERZ has been characterized in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 2 steps
  1. 2017 High

    Established that CATSPERZ is a bona fide subunit of the CatSper complex and defined its role in organizing the channel's nanodomain architecture rather than carrying the pore.

    Evidence Knockout mouse with CatSper current electrophysiology, STORM super-resolution imaging of flagellar nanodomains, and rheotaxis/IVF assays

    PMID:28226241

    Open questions at the time
    • Molecular mechanism by which CATSPERZ enforces the ~0.8 μm quadrilateral nanodomain spacing is unresolved
    • Direct physical interactions with specific CatSper subunits not mapped
    • No structural model of how CATSPERZ integrates into the channel complex
  2. 2018 Low

    Asked whether reduced CATSPERZ levels associate with human sperm dysfunction, linking the protein's abundance to calcium entry and motility defects.

    Evidence 2D-DIGE proteomics, mass spectrometry, western blot and ELISA on asthenozoospermic patient spermatozoa

    PMID:30550884

    Open questions at the time
    • Correlative only; no functional manipulation of CATSPERZ was performed
    • Causality between lowered TEX40 protein and reduced calcium influx not established
    • Does not confirm the structural role observed in mouse applies in human sperm

Open questions

Synthesis pass · forward-looking unresolved questions
  • How CATSPERZ molecularly directs nanodomain assembly and which subunit contacts mediate its organizing function remain unknown.
  • No interaction map or structural data for CATSPERZ within the CatSper complex
  • Mechanism coupling nanodomain integrity to flagellar flexibility undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 1
Localization
GO:0005886 plasma membrane 1 GO:0005929 cilium 1
Pathway
R-HSA-1474165 Reproduction 1
Complex memberships
CatSper channel complex

Evidence

Reading pass · 2 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2017 CATSPERZ (encoded by Tex40) is a novel subunit of the 9-subunit CatSper ion channel complex in sperm. Targeted disruption of CatSperζ reduces CatSper current and disrupts the linear quadrilateral nanodomain organization of the CatSper complex along the flagellum at ~0.8 μm intervals, rendering the proximal flagellum inflexible and altering the 3D flagellar envelope, resulting in severe male subfertility due to impaired rheotaxis and in vivo migration. Targeted gene disruption (knockout mouse), electrophysiology (CatSper current measurement), super-resolution fluorescence imaging (STORM), sperm motility and rheotaxis assays, in vitro fertilization eLife High 28226241
2018 Lower expression of TEX40 (CATSPERZ) protein in spermatozoa from asthenozoospermic males correlates with reduced calcium ion entry, consistent with its role as a component of the CatSper channel complex required for normal sperm motility. 2D-DIGE proteomics, mass spectrometry, western blotting, ELISA, qRT-PCR Life sciences Low 30550884

Source papers

Stage 0 corpus · 6 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 CatSperζ regulates the structural continuity of sperm Ca2+ signaling domains and is required for normal fertility. eLife 129 28226241
2018 Homozygous in-frame deletion in CATSPERE in a man producing spermatozoa with loss of CatSper function and compromised fertilizing capacity. Human reproduction (Oxford, England) 46 30239785
2011 ESRRA-C11orf20 is a recurrent gene fusion in serous ovarian carcinoma. PLoS biology 43 21949640
2018 Proteomic analyses reveal lower expression of TEX40 and ATP6V0A2 proteins related to calcium ion entry and acrosomal acidification in asthenozoospermic males. Life sciences 17 30550884
2014 Low frequency of ESRRA-C11orf20 fusion gene in ovarian carcinomas. PLoS biology 10 24504521
2023 Integrated single cell transcriptome sequencing analysis reveals species-specific genes and molecular pathways for pig spermiogenesis. Reproduction in domestic animals = Zuchthygiene 4 37874861

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