Y-shaped link

GO:0097537 · Appendage · Multiprotein complex · Proposed

A Y-shaped protein complex in the ciliary transition zone that connects the cilium axoneme to the ciliary necklace. Both protein sorting and protein gating occur at this point in the cilium allowing some, but not all proteins to enter the cilium. [GO:0097537]

Image (not hosted — OTHER): PMC2935561.1:fig3

Wild-type and cep290 Chlamydomonas transition zones. Panels C-D compare Y-connectors in cross section; A-B show longitudinal wedge densities; E-G show mutant flagellar defects, H compares membrane spacing, and I-J compare detergent-extracted transition zones. Scale bars vary by panel; the C-D insets are image averages, not individual linkers. TEM · Chlamydomonas reinhardtii (NCBITaxon:3055) · Branch Craige, Che-Chia Tsao, Dennis R. Diener, Yuqing Hou, Karl-Ferdinand Lechtreck, Joel L. Rosenbaum and George B. Witman; 2010, CC BY-NC-SA 3.0, via PubMed Central. · OTHER · source: PMC PMC2935561.1:fig3 · DOI:10.1083/jcb.201006105

Synonyms: membrane-microtubule complex; Y-link; Y-link structure; Y-shaped assemblage; Y-shaped fiber; Y-shaped fibre; Y-shaped linker

Part of: ciliary transition zone (GO:0035869)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
Centrosomal protein of 290kDa	Protein	part of	`InterPro:IPR026201`	CEP290, POC3		UNKNOWN	A linker-associated constituent supporting normal microtubule-membrane connector architecture in Chlamydomonas. It is not the entire linker; rare Y-connectors persist in the cep290 null mutant, so absolute assembly essentiality is not asserted. `DOI:10.1083/jcb.201006105` Immunogold localization in Figure 4 places the middle region of CEP290 on or near Y-connectors; Figure 3 shows most connectors absent or abnormal in the deletion mutant. The authors explicitly report rare remaining Y-connectors and infer additional constituents. `InterPro:IPR026201` Live InterPro metadata verifies the family type and the canonical label Centrosomal protein of 290kDa; it does not supply linker stoichiometry.

Canonical examples

NCBITaxon:3055 Chlamydomonas reinhardtii — Wild-type, cep290 deletion and complemented cells were examined. Transition-zone cross sections resolve peripheral Y-connectors; immunogold microscopy and detergent-extraction assays link CEP290 to connector architecture and membrane attachment. [DOI:10.1083/jcb.201006105]

Functions

transition-zone membrane tethering — Microtubule-membrane connectors physically couple the transition-zone doublets to the surrounding ciliary membrane. The Chlamydomonas evidence concerns the connector ensemble, not purified Y-links acting alone.
- DOI:10.1083/jcb.201006105 Figure 3 compares connector defects with greater and more variable membrane spacing and loss of detergent-resistant membrane attachment in cep290 cells.

Mechanism graphs

CEP290-supported connector architecture and membrane tethering (FUNCTION)

A bounded physical mechanism supported by Chlamydomonas localization, mutant ultrastructure and membrane-extraction experiments.

Subject	Predicate	Object	Evidence
Centrosomal protein of 290kDa	supports normal architecture of	Y-shaped link	`DOI:10.1083/jcb.201006105` Figures 3C-D and 4 combine mutant cross sections with immunogold placement. Rare surviving Y-connectors limit the claim to normal architecture rather than absolute assembly dependence.
Y-shaped link	contributes to	transition-zone membrane tethering to microtubule doublets	`DOI:10.1083/jcb.201006105` Figure 3 shows cross-sectional links between doublets and membrane; connector disruption accompanies increased membrane spacing and loss of membrane retention after detergent extraction. Wedge densities are also affected, so this is not Y-link-specific sufficiency.

Discussions

CURATION_TODO (RESOLVED): Distinguish the Y-shaped linker subassembly from adjacent ciliary structures. The existing ciliary-transition-zone record already mentions Y-linkers as an architectural component, but denotes the whole region. GO:0097537 denotes the discrete linker complex and is linked here by part_of, not treated as a synonym of that region.
CURATION_TODO (OPEN): Resolve additional linker constituents and the exact experimental CEP290 protein accession. Residual Y-links in the cep290 null mutant show that CEP290 is not the complete molecular inventory. UniProt text searches yield multiple unreviewed Chlamydomonas models without the experimental paper citation; a family match alone does not establish the exact protein example.
CURATION_TODO (OPEN): Resolve which linker-specific interactions control ciliary protein entry or retention. CEP290 loss changes ciliary protein composition, but it also disrupts multiple connector features. Those phenotypes do not isolate the Y-link contribution or demonstrate a particular binding or transport reaction.

Evidence

GO:0097537 Exact GO identity, definition and related synonyms for the named linker subassembly.
DOI:10.1083/jcb.201006105 Craige et al. 2010, CEP290 tethers flagellar transition zone microtubules to the membrane and regulates flagellar protein content. Primary Results, Discussion, methods and Figures 3-4 inspected from official PMC OA JATS and checksum-verified figures.
PMID:20819941 PubMed bibliographic identity for the Craige et al. primary study.

Curation history

2026-10-04T06:09:30Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-04T06:11:13Z codex · EXPANDED_RECORD — Added exact GO synonymy and transition-zone parthood, verified CEP290 family, Chlamydomonas canonical example, bounded physical tethering function and mechanism, link-only primary microscopy and explicit composition, accession and gating uncertainties.

Source: data/structures/appendage/y_shaped_link.yaml