ejectisome

cellstructuremech:ejectisome · Other · Other · Proposed

A cryptophyte extrusive organelle that discharges proteinaceous paracrystalline ribbons or filaments built in part from small ejectisin polypeptides. [DOI:10.1007/s00709-012-0440-4]

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
ejectisin polypeptides	Protein	part of	Reviewed label only (reviewed name; no accession asserted)			UNKNOWN	Small, approximately 6-kDa polypeptides that make up a major component of cryptophycean ejectisomes. `DOI:10.1007/s00709-012-0440-4` Ammermann et al. 2013 found 6-kDa polypeptides dominating isolated and reconstituted cryptophyte ejectisome fragments, and introduced the name ejectisins for those major ejectisome components.

Taxonomic distribution

NCBITaxon:3027 Cryptophyceae — VARIABLE: Ejectisomes were isolated from Chroomonas and Cryptomonas species, and ejectisin components are described as cryptophycean; this record does not assert that every Cryptophyceae species carries ejectisomes. [DOI:10.1007/s00709-012-0440-4]

Canonical examples

NCBITaxon:3028 Chroomonas — Cryptophyte genus represented among the cultures used to isolate and characterize discharged ejectisomes and ejectisin-rich ejectisome filaments. [PMID:22868567]

Mechanism graphs

Ejectisins are major components of discharged ejectisomes (FUNCTION)

Cryptophyte ejectisomes contain small ejectisin polypeptides and discharge as tubular or filamentous proteinaceous structures with a paracrystalline lattice.

Subject	Predicate	Object	Evidence
ejectisin polypeptides	are major component of	ejectisome	`DOI:10.1007/s00709-012-0440-4` Ammermann et al. 2013 found the isolated ejectisome-fragment protein pattern was dominated by 6-kDa polypeptides and named those major components ejectisins.
ejectisome	discharges as	discharged ejectisome filaments	`DOI:10.1007/s00709-011-0267-4` Rhiel and Westermann 2012 purified discharged ejectisomes from Chroomonas and Cryptomonas species and measured paracrystalline periodicity in tubular fragments.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral InterPro, Pfam or NCBIfam grounding for the cryptophyte 6-kDa ejectisin polypeptides. Ejectisins were identified as major cryptophycean ejectisome components, but this pass did not verify a curated family accession that exactly denotes those small structural polypeptides.
CURATION_TODO (OPEN): Resolve the undischarged ejectisome membrane context, ribbon substructure names and species-level cryptophyte culture boundaries. The current graph is limited to isolated discharged ejectisome fragments from a Chroomonas and two Cryptomonas species; the mature resting architecture, membrane boundary and exact culture species need further curation before adding substructures.

Evidence

DOI:10.1007/s00709-011-0267-4 Rhiel and Westermann 2012 isolated discharged ejectisomes from pigmented cryptophytes and characterized their tubular paracrystalline fragments by transmission electron microscopy.
DOI:10.1007/s00709-012-0440-4 Ammermann et al. 2013 purified Chroomonas and Cryptomonas ejectisome fragments and identified ejectisins as major cryptophycean ejectisome polypeptides.
PMID:21336864 PubMed record for the Rhiel and Westermann 2012 discharged ejectisome ultrastructure study.
PMID:22868567 PubMed record for the Ammermann et al. 2013 ejectisin component study.

Curation history

2026-09-22T10:18:59Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-22T10:20:21Z codex · EXPANDED_RECORD — Added a label-only ejectisin component, Cryptophyceae and Chroomonas scope, DOI and PMID evidence, a nonmechanistic discharged-ejectisome filament graph, and TODOs for ejectisin grounding and ejectisome boundaries.
2026-09-22T10:46:35Z codex · ADDRESS_REVIEW — Resolved PR #1272 review issue #1273 by adding GO:0043231 as the broader parent_structures term for the minted ejectisome record.

Source: data/structures/other/ejectisome.yaml