basal body pinhead

cellstructuremech:basal_body_pinhead · Cytoskeleton · Multiprotein complex · Proposed

A proteinaceous subassembly on the luminal face of the A-tubule in the proximal region of a microbial ciliary basal body or pro-basal body, forming the peripheral connection toward the cartwheel spokes. In Chlamydomonas reinhardtii it has a bent pinbody and two pinfeet attached to protofilament A3. [DOI:10.7554/eLife.43434]

Chlamydomonas proximal triplet reconstructions. Panel D highlights the pinhead in pink, with PinB, PinF1 and PinF2 labeled and an 8-nm axial repeat. Panels A-C instead show tubule reconstructions and neighboring MIPs. Each row has a 10-nm scale bar. These are averaged density renderings, not raw micrographs. CRYO_ET · *Chlamydomonas reinhardtii* (`NCBITaxon:3055`) · Sam Li, Jose-Jesus Fernandez, Wallace F Marshall, David A Agard; CC BY 4.0, via PubMed Central · CC_BY_4_0 · source: PMC PMC6384029.1 fig2 · `DOI:10.7554/eLife.43434`

Synonyms: centriole pinhead

Part of: ciliary basal body (GO:0036064); GO:0120280 — ciliary pro-basal body (no local record)

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
Bld10/Cep135	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	BLD10, CEP135		UNKNOWN	Cartwheel spoke-tip constituent in Chlamydomonas, supported by the primary report of immuno-EM localization and truncation morphology. This is not a sequence assignment to PinB, PinF1 or PinF2 in the subtomogram average, nor a claim that Bld10 is confined to the pinhead. `DOI:10.1016/j.cub.2007.09.021` The inspected primary abstract reports Bld10 as a major spoke-tip component based on immuno-EM and truncated-protein morphology. Only the abstract was accessible; full Results, Methods and figures were not inspected. Detailed mutant measurements are not curated here.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

Bld10/Cep135

Accession	Protein	Gene	Organism	Entry
`UniProtKB:A8ID55`	Basal body protein 10	BLD10	Chlamydomonas reinhardtii (`NCBITaxon:3055`)	REVIEWED
Role and evidence (2 references) `UniProtKB:A8ID55` Native UniProt JSON verifies accession, recommended name, gene, taxon and Swiss-Prot status; it is not independent pinhead imaging. `DOI:10.1016/j.cub.2007.09.021` Membership is supported at the inspected primary-abstract level, not by a residue-resolved model.

Canonical examples

NCBITaxon:3055 Chlamydomonas reinhardtii — Cryo-ET and local subtomogram classification of isolated nuclear-flagellar apparatuses resolve pinheads in pro-basal bodies and the proximal region of mother basal bodies. This is not an assertion of pinhead occupancy along the entire basal-body length. [DOI:10.7554/eLife.43434]

Functions

ciliary basal body organization GO:0032053 — Forms the peripheral structural connection between cartwheel spokes and the A-tubule wall in the characterized Chlamydomonas proximal region. This observed connection does not by itself establish a force response, a length-control mechanism or an assembly time course.
- DOI:10.7554/eLife.43434 Results and Figures 1 and 2 resolve the connection and the A3-associated pinbody/pinfeet morphology.

Physical properties

OTHER: 8 UO:0000018 (Axial pinhead repeat in the Chlamydomonas proximal mother-basal-body and pro-basal-body reconstruction, Li et al. 2019 Figure 2D. Each pair of pinfeet associates with an alpha/beta-tubulin dimer on A3. This is not the length of a pinhead or a repeat generalized to other species.) [DOI:10.7554/eLife.43434]

Discussions

CURATION_TODO (RESOLVED): Distinguish the pinhead from its cartwheel and microtubule neighbors. A named peripheral assembly is neither an entire basal body nor a single protein.
CURATION_TODO (OPEN): Resolve the pinhead proteome and exact Bld10/Cep135 family grounding. Localization and domain matches do not assign all resolved densities or a complete proteome.
CURATION_TODO (RESOLVED): Avoid transferring cartwheel and triplet identities into the pinhead. Being part of the same basal body does not establish membership in every subassembly.
CURATION_TODO (RESOLVED): Keep repeat measurements separate from map dimensions and assembly hypotheses. Static reconstruction, image processing and proposed mechanics answer different questions.

Datasets

Chlamydomonas pinhead with associated partial A-tubule (EMDB:EMD-9171) · OTHER · STRUCTURAL_IMAGING
Organism: Chlamydomonas reinhardtii · Platform: cryo-electron tomography and subtomogram averaging
Released EMDB metadata explicitly identifies the pinhead-associated map, taxon 3055, strain CC849 and the primary DOI/PMID. Its 4763 subtomograms and 23.1-angstrom resolution are reconstruction provenance, not biological counts or dimensions. The map includes tubulin and is not an exact xref for the pinhead alone. No map volume is hosted.

Evidence

DOI:10.7554/eLife.43434 Li et al. 2019, PMID:30741631. Checksum-verified PMC6384029.1 JATS pinhead Results, Discussion, reconstruction and periodicity-control Methods, Table 3 and Figure 2 inspected. The original Figure 2 was visually inspected; no sequence assignment follows from its densities.
DOI:10.1016/j.cub.2007.09.021 Hiraki et al. 2007, PMID:17900905. Primary abstract inspected through Europe PMC; publisher PDF and full-text routes were inaccessible on 2026-10-04. Only the abstract-supported Bld10 spoke-tip membership is used.

Curation history

2026-10-04T13:45:54Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-04T13:47:45Z codex · CURATED_RECORD — Added pinhead architecture, Chlamydomonas example, 8-nm repeat, scoped Bld10 membership, native EMDB dataset and inspected CC BY figure. Kept density assignments and inaccessible full-text follow-up explicit; no universal composition or assembly chronology asserted.

Source: data/structures/cytoskeleton/basal_body_pinhead.yaml