telocentrosome

cellstructuremech:telocentrosome · Cytoskeleton · Multiprotein complex · Proposed

A telomere-associated microtubule organizing assembly formed at the nuclear envelope during meiotic entry in Schizosaccharomyces pombe. It recruits a gamma-tubulin nucleation complex to SUN/KASH-linked telomeres and generates cytoplasmic microtubules that support their clustering at the spindle pole body; it is distinct from the spindle pole body and the completed telomere bouquet. [DOI:10.1083/jcb.201207168]

Image (not hosted — OTHER): PMC3575533.1 fig2

Multipanel Figure 2: A follows telomeres and microtubules before conjugation; B is the haploid-meiosis schematic; C compares MBC and solvent controls. D-E follow telomere-associated microtubule regrowth and clustering after MBC washout in induced haploid meiosis. Microscopy scale bars are 2 micrometers; graphs and schematic are not micrographs. FLUORESCENCE · Schizosaccharomyces pombe (NCBITaxon:4896) · Masashi Yoshida, Satoshi Katsuyama, Kazuki Tateho, Hiroto Nakamura, Junpei Miyoshi, Tatsunori Ohba, Hirotada Matsuhara, Futaba Miki, Koei Okazaki, Tokuko Haraguchi, et al.; CC BY-NC-SA 3.0, via PubMed Central · OTHER · source: PMC PMC3575533.1 fig2 · DOI:10.1083/jcb.201207168

Synonyms: meiotic telomeric MTOC

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
SUN domain-containing protein 1-5	Protein	part of	`InterPro:IPR045119`	sad1	UNKNOWN	Nuclear-envelope SUN component marking telomere-associated nucleation sites. `DOI:10.1083/jcb.201207168` Figure 3A localizes Sad1 with unclustered Taz1-marked telomeres before conjugation; Supplementary Figure S2D observes microtubule regrowth from Sad1 foci. `InterPro:IPR045119` Authority label and scope checked on 2026-10-05; the primary paper, not the family match alone, establishes residence.
Kms1-like KASH protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	kms1	UNKNOWN	Resident envelope linker required for normal recruitment of Mto1, Dlc1 and the gamma-tubulin complex. `DOI:10.1083/jcb.201207168` Figure 3B-D localizes Kms1 at Sad1-marked telocentrosomes and tests recruitment dependencies; reduced or residual signals do not justify an all-or-none stoichiometric claim.
Kms2-like KASH protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	kms2	UNKNOWN	Second resident KASH protein at telomere-associated envelope sites. `DOI:10.1083/jcb.201207168` Figure 3A-B colocalizes Kms2 with multiple Sad1 foci before conjugation; this experiment does not establish its individual assembly essentiality.
Mto1-like microtubule nucleation adaptor	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	mto1	UNKNOWN	Resident adaptor supporting telomeric recruitment of the gamma-tubulin nucleation complex. `DOI:10.1083/jcb.201207168` Figures 3D, 4 and 5 place Mto1 at telocentrosomes and show greatly reduced Alp4 recruitment and severe clustering defects after mto1 loss.
gamma-tubulin complex	Protein complex	part of	`GO:0000930`	alp4	UNKNOWN	Microtubule-nucleating subcomplex recruited to the telomere environment; Alp4 is the directly imaged constituent. `DOI:10.1083/jcb.201207168` Figures 3D, 4D and 5 use Alp4 as a gamma-tubulin-complex reporter. This supports complex recruitment without establishing ring geometry, a small-complex stoichiometry, or direct localization of every subunit. `GO:0000930` Authority label and scope checked on 2026-10-05; the primary paper, not the family match alone, establishes residence.
Dynein light chain Tctex-1-like	Protein	part of	`InterPro:IPR005334`	dlc1	UNKNOWN	Resident light-chain class with a contribution to gamma-tubulin-complex recruitment separable from heavy-chain motor activity. `DOI:10.1083/jcb.201207168` Figures 3C and 5 show Kms1-dependent Dlc1 localization, independent Dhc1 recruitment, and reduced Alp4 telomere localization after dlc1 deletion. Early and later stages differ. `InterPro:IPR005334` Authority label and scope checked on 2026-10-05; the primary paper, not the family match alone, establishes residence.
Cytoplasmic dynein heavy chain	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	dhc1	DISPENSABLE	Resident motor-bearing dynein subunit contributing to telomere clustering. `DOI:10.1083/jcb.201207168` Figure 3C/E localizes Dhc1 and a motor-domain-deleted fragment at Sad1 foci. Figure 5 shows that Alp4 still localizes in dhc1-deleted cells, supporting dispensability for nucleation-center recruitment rather than dispensability for efficient clustering.
Ssm4-like dynactin p150 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ssm4	UNKNOWN	Resident dynactin-associated microtubule-binding subunit recruited in a Dhc1-dependent manner. `DOI:10.1083/jcb.201207168` Figure 3C localizes Ssm4 at telocentrosomes and shows loss of recruitment without Dhc1; Figure 1C reports an enhanced clustering defect in the dhc1 deletion background.

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.

SUN domain-containing protein 1-5

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q09825`	Spindle pole body-associated protein sad1	sad1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figure 3A localizes Sad1 with unclustered Taz1-marked telomeres before conjugation; Supplementary Figure S2D observes microtubule regrowth from Sad1 foci. `https://www.uniprot.org/uniprotkb/Q09825/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Kms1-like KASH protein

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P87245`	Karyogamy meiotic segregation protein 1	kms1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figure 3B-D localizes Kms1 at Sad1-marked telocentrosomes and tests recruitment dependencies; reduced or residual signals do not justify an all-or-none stoichiometric claim. `https://www.uniprot.org/uniprotkb/P87245/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Kms2-like KASH protein

Accession	Protein	Gene	Organism	Entry
`UniProtKB:O43087`	Karyogamy meiotic segregation protein 2	kms2	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figure 3A-B colocalizes Kms2 with multiple Sad1 foci before conjugation; this experiment does not establish its individual assembly essentiality. `https://www.uniprot.org/uniprotkb/O43087/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Mto1-like microtubule nucleation adaptor

Accession	Protein	Gene	Organism	Entry
`UniProtKB:O94488`	Gamma tubulin complex adapter mto1	mto1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figures 3D, 4 and 5 place Mto1 at telocentrosomes and show greatly reduced Alp4 recruitment and severe clustering defects after mto1 loss. `https://www.uniprot.org/uniprotkb/O94488/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

gamma-tubulin complex

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q9Y705`	Spindle pole body component alp4	alp4	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Alp4 is one imaged subunit and reporter of the gamma-tubulin complex, not a protein accession for the entire complex. Reference-sequence exemplar; no exact-stock assertion. `DOI:10.1083/jcb.201207168` Figures 3D, 4D and 5 use Alp4 as a gamma-tubulin-complex reporter. This supports complex recruitment without establishing ring geometry, a small-complex stoichiometry, or direct localization of every subunit. `https://www.uniprot.org/uniprotkb/Q9Y705/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Dynein light chain Tctex-1-like

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q9UTS6`	Dynein light chain Tctex-type	dlc1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figures 3C and 5 show Kms1-dependent Dlc1 localization, independent Dhc1 recruitment, and reduced Alp4 telomere localization after dlc1 deletion. Early and later stages differ. `https://www.uniprot.org/uniprotkb/Q9UTS6/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Cytoplasmic dynein heavy chain

Accession	Protein	Gene	Organism	Entry
`UniProtKB:O13290`	Dynein heavy chain, cytoplasmic	dhc1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figure 3C/E localizes Dhc1 and a motor-domain-deleted fragment at Sad1 foci. Figure 5 shows that Alp4 still localizes in dhc1-deleted cells, supporting dispensability for nucleation-center recruitment rather than dispensability for efficient clustering. `https://www.uniprot.org/uniprotkb/O13290/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Ssm4-like dynactin p150 subunit

Accession	Protein	Gene	Organism	Entry
`UniProtKB:O42667`	Microtubule-associated protein ssm4	ssm4	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for the species-level localization experiment; not an assertion that this exact reference stock was imaged. `DOI:10.1083/jcb.201207168` Figure 3C localizes Ssm4 at telocentrosomes and shows loss of recruitment without Dhc1; Figure 1C reports an enhanced clustering defect in the dhc1 deletion background. `https://www.uniprot.org/uniprotkb/O42667/entry` Reviewed status, primary gene, protein label and source taxon verified natively on 2026-10-05. Localization is supported by the primary experiment.

Canonical examples

NCBITaxon:4896 Schizosaccharomyces pombe — Defined in zygotic meiosis and experimentally synchronized mat-gene-induced haploid meiosis. The 2025 ectopic mitotic experiment is a partial reconstitution, not evidence of constitutive mitotic occurrence or broad fungal prevalence. [DOI:10.1083/jcb.201207168]

Functions

microtubule nucleation by microtubule organizing center GO:0051418 — Nucleates cytoplasmic microtubules at telomere-associated sites during the tested meiotic conditions.
- DOI:10.1083/jcb.201207168 Figure 2D-E and Supplementary Figure S2 use microtubule regrowth after MBC removal; Sad1-marked sites also nucleate microtubules before zygotic conjugation.
meiotic telomere clustering GO:0045141 — Supports motor-dependent gathering of telomeres toward the spindle pole body.
- DOI:10.1083/jcb.201207168 Live dynamics, MBC inhibition and kms1/mto1 perturbations connect telocentrosome activity to clustering. A microtubule-nucleating focus alone is not claimed sufficient for a complete bouquet.

Mechanism graphs

Recruitment dependencies at meiotic telomeres (ASSEMBLY)

Subject	Predicate	Object	Evidence
Kms1-like KASH protein	supports	Mto1-like microtubule nucleation adaptor	`DOI:10.1083/jcb.201207168` Figure 3D: reduced Mto1 localization in kms1-deleted cells. The edge specifies recruitment dependence, not direct binding.
Kms1-like KASH protein	supports	Dynein light chain Tctex-1-like	`DOI:10.1083/jcb.201207168` Figure 3C: Dlc1 localization depends on Kms1, independently of Dhc1.
Mto1-like microtubule nucleation adaptor	supports	gamma-tubulin complex	`DOI:10.1083/jcb.201207168` Figures 3D, 4D and 5B: Alp4 localization is substantially reduced after mto1 deletion.
Dynein light chain Tctex-1-like	supports	gamma-tubulin complex	`DOI:10.1083/jcb.201207168` Figure 5B shows reduced Alp4 localization in dlc1-deleted haploid meiotic cells; early preconjugation recruitment can remain, so absolute initial assembly essentiality is not asserted.
gamma-tubulin complex	supports	Telocentrosome	`DOI:10.1083/jcb.201207168` Figures 2-5 combine regrowth, Alp4 localization and recruitment mutants; this is the source's assembly interpretation, not evidence that isolated gamma-TuC alone is sufficient.

Telomeric microtubules support clustering (FUNCTION)

Subject	Predicate	Object	Evidence
Telocentrosome	supports	microtubule nucleation by microtubule organizing center	`DOI:10.1083/jcb.201207168` Figure 2D and Supplementary Figure S2 observe microtubule regrowth near telomeres after MBC washout.
microtubule nucleation by microtubule organizing center	supports	meiotic telomere clustering	`DOI:10.1083/jcb.201207168` Figure 2 observes telomeres gathering after microtubule connection, and MBC inhibits clustering; Figure 1 identifies motor contributions. This edge does not claim nucleation alone is sufficient.

Discussions

CURATION_TODO (RESOLVED): Keep the telomeric nucleation assembly distinct from its tether, products and clustering endpoint.
CURATION_TODO (OPEN): Find exact whole-protein family groundings for five label-only component classes.
CURATION_TODO (RESOLVED): Disambiguate native gene-name collisions.
CURATION_TODO (RESOLVED): Do not infer architecture or absolute necessity from reporter localization.
CURATION_TODO (RESOLVED): Separate the nucleation-center core from upstream chromosome tethers and external motor systems.
KNOWLEDGE_GAP (OPEN): Resolve the physical motor arrangement without promoting a proposed model to fact.
CURATION_TODO (RESOLVED): Keep partial ectopic assembly separate from physiological meiotic telocentrosomes.
CURATION_TODO (RESOLVED): Keep organism and measurement claims within the available evidence.
CURATION_TODO (RESOLVED): Retain the original figure as a source link, with exact licence and context.

Evidence

DOI:10.1083/jcb.201207168 Yoshida et al. 2013, PMID 23401002; native PMC3575533.1 Results, relevant imaging/meiotic-induction Methods and figure captions read. Figure 2 inspected unchanged after checksum verification.
DOI:10.1038/s41467-025-56049-9 Jimenez-Martin et al. 2025, PMID 39833200; native PMC11747273.1 telocentrosome recruitment, kms1 suppression and microscopy Methods read. Ectopic Bqt1/Bqt2 in Rabl-deficient mitotic cells recruits Sad1/Kms1/Mto1/Alp4 without detectable Dhc1 or a complete bouquet.
GO:0005815 Non-obsolete native GO cellular-component term is broader than the telomeric nucleation assembly.

Curation history

2026-10-05T19:43:01Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-05T19:43:50Z codex · EXPANDED_RECORD — Added eight component classes and eight verified protein examples, bounded assembly and function graphs, a link-only inspected primary figure, and explicit identity, evidence and family-grounding limits.

Source: data/structures/cytoskeleton/telocentrosome.yaml