basal body inner scaffold

cellstructuremech:basal_body_inner_scaffold · Cytoskeleton · Multiprotein complex · Proposed

A proteinaceous meshwork lining the lumen-facing surface of the central basal-body wall and interconnecting neighboring triplet microtubules through multiple attachment sites. [DOI:10.1083/jcb.202311104]

Representative density rendering of a wild-type Tetrahymena central-core basal-body triplet with associated luminal attachments. This is a subtomogram average, not a raw micrograph, complete scaffold ring or identification of individual proteins. No scale bar is shown. CRYO_ET · *Tetrahymena thermophila* (`NCBITaxon:5911`) · Ruehle M, Li S, Agard DA, Pearson C; EMDB depositor representative figure, without copyright restrictions. · PUBLIC_DOMAIN · source: EMDB EMD-42777 · `DOI:10.1083/jcb.202311104`

Part of: ciliary basal body (GO:0036064)

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
POC1 family protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	POC1		UNKNOWN	Anchors the scaffold at the central-core A-B inner junction. Its WD40 domain contacts an unidentified stem protein connecting toward the scaffold. This role does not assign Poc1 to the central-core B-C junction. `DOI:10.1083/jcb.202311104` Figures 5D-E and 6C combine model fitting and loss of the corresponding density in poc1 deletion material. Scaffold density is nearly absent in the mutant; initial assembly versus subsequent maintenance is not separated.
FAM161A family protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	FAM161A		UNKNOWN	Inner-scaffold-associated constituent supported by endogenous-tag localization at the basal-body core and reduced basal-body signal after Poc1 loss. Its exact position within the scaffold and direct binding partners in Tetrahymena remain unassigned; additional distal localization is present. `DOI:10.1083/jcb.202311104` Results and Figures 5A, 6A and S5 support the homolog assignment and localization. Unlike Poc1, Fam161A has no assigned molecular cryo-ET density here. Human-protein interaction results cited by the article are not direct evidence of a Tetrahymena Poc1-Fam161A contact.

Canonical examples

NCBITaxon:5911 Tetrahymena thermophila — Cryotomography of isolated wild-type and poc1-deletion basal bodies resolves the central-core scaffold and its attachments. Endogenous Fam161A tagging and fluorescence imaging provide complementary localization evidence. Methods list B2086 and SB1969 backgrounds; this example is species-level, not an asserted strain-specific pairing with SB210 reference sequences. [DOI:10.1083/jcb.202311104]

Functions

intertriplet cohesion — Provides luminal connections between neighboring basal-body triplet microtubules in the central core. In the studied Tetrahymena material, backfitted reconstructions support stacked rings rather than a universal helical geometry.
- DOI:10.1083/jcb.202311104 Figure 5B-C and Figure S4E support the intertriplet meshwork and ring arrangement. This structural function does not assert a measured force threshold or selective scaffold-dependent rescue of basal-body shape.

Mechanism graphs

Poc1 anchors a luminal intertriplet scaffold (FUNCTION)

Structural contacts and a separately bounded localization dependency in the Tetrahymena basal-body central core.

Subject	Predicate	Object	Evidence
POC1 family protein	binds at the A-B inner junction of	central-core basal-body triplet microtubules	`DOI:10.1083/jcb.202311104` Figure 5D-E and Video 4 support placement and mutant density loss.
POC1 family protein	contacts	unassigned A-B junction stem density	`DOI:10.1083/jcb.202311104` Figure 6C resolves contiguous densities; both disappear in poc1 deletion material.
unassigned A-B junction stem density	connects toward	basal body inner scaffold	`DOI:10.1083/jcb.202311104` Figures 5D and 6C and Results support the structural attachment model.
basal body inner scaffold	interconnects	central-core basal-body triplet microtubules	`DOI:10.1083/jcb.202311104` Figure 5B-C and Results show multiple attachments and lateral connections.
POC1 family protein	supports normal levels of	basal-body Fam161A localization signal	`DOI:10.1083/jcb.202311104` Figure 6A compares total-cell-normalized basal-body signal at 30 degrees C (p = 0.0079). This is a perturbation dependency, not evidence of direct binding or complete recruitment dependence.

Discussions

CURATION_TODO (RESOLVED): Distinguish the inner scaffold from adjacent basal-body structures. The imaged intertriplet meshwork is a physical entity, not a single protein or the whole basal body.
CURATION_TODO (OPEN): Resolve exact POC1 and FAM161A family groundings without substituting broader families. A combined family or domain is not an exact identity for a narrower component class.
CURATION_TODO (OPEN): Identify the stem and other attachment proteins and locate Fam161A within the scaffold. The two named classes are not a complete composition or a molecular model of every scaffold density.
CURATION_TODO (RESOLVED): Do not import nearby proteins or human scaffold composition as demonstrated Tetrahymena constituents. Colocalization and evidence from another organism do not by themselves establish the same molecular placement.
CURATION_TODO (RESOLVED): Keep mechanical interpretations and geometric measurements within their assay scope. Poc1 loss affects multiple modules, and preparation-induced deformation is not a direct in-cell force measurement.

Datasets

Wild-type basal-body central-core triplet microtubule (EMDB:EMD-42777) · OTHER · STRUCTURAL_IMAGING
Organism: Tetrahymena thermophila · Platform: cryo-electron tomography and subtomogram averaging
Released EMDB metadata, natural-source taxon 5911 and exact primary citation verified. Only metadata and the representative PNG are retained, not volume maps.
Wild-type central-core A-B inner junction (EMDB:EMD-42782) · OTHER · STRUCTURAL_IMAGING
Organism: Tetrahymena thermophila · Platform: cryo-electron tomography and focused subtomogram averaging
Released native EMDB metadata inspected; the reconstruction is a subregion, not whole-scaffold identity.
Poc1-knockout basal-body central-core triplet microtubule (EMDB:EMD-42784) · OTHER · STRUCTURAL_IMAGING
Organism: Tetrahymena thermophila · Platform: cryo-electron tomography and subtomogram averaging
Released native EMDB metadata inspected. Poc1 loss is pleiotropic and is not a selective ablation of only the inner scaffold.

Evidence

DOI:10.1083/jcb.202311104 Ruehle et al. 2024. Official checksum-verified PMC11094743.1 JATS, core-region Results and Discussion, relevant Methods, tables and figure captions read. Figures 5, 6 and S4 inspected visually. No verbatim snippets are asserted.
PMID:38743010 Bibliographic identity verified against the official PMC and EMDB primary citations.

Curation history

2026-10-04T08:39:14Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-04T08:40:37Z codex · EXPANDED_RECORD — Added bounded Tetrahymena inner-scaffold composition, structural-contact graph, EMDB datasets and licensed density preview; preserved unknown molecular assignments, assay scope and family-grounding uncertainty.

Source: data/structures/cytoskeleton/basal_body_inner_scaffold.yaml