exocytosis

traitmech:000637 · CLASS · PROPOSED

A physiological phenotype in which a microbial cell releases material from an intracellular membrane-bounded compartment to the cell exterior through a fusion pore between the compartment membrane and the plasma membrane.

Trait evidence (3)

DOI:10.1083/jcb.56.1.153
The cytoplasm between the two matching membrane sites is squeezed away and the membranes fuse

PMID:4629881, PMC2108847. Scientific Abstract directly read in Europe PMC XML and PubMed. The quote retains the source's missing terminal punctuation. Freeze-fracture/etch observations in the historically named Tetrahymena pyriformis system connect mucocyst-plasma-membrane fusion, opening enlargement and contents release. Fixation triggers some discharge. Abstract-level evidence does not establish a universal pore size or fusion machinery. The XML has sparse body content and the PDF endpoint returned HTML; full methods, figures and strain provenance were not inspected.
DOI:10.1007/BF01870409
Upon returning the cells to the permissive temperature the contents of the accumulated vesicles were secreted.

PMID:1744905. Scientific Abstract directly read in NCBI PubMed XML and Europe PMC metadata, which agree on the DOI. Constitutive secretion in Saccharomyces cerevisiae is examined using temperature-sensitive sec mutants, accumulated vesicles and blocked protein synthesis. Calcium perturbations did not affect the measured release under these conditions; this does not establish calcium irrelevance in every yeast context. No universal rate or requirement for extracellular stimulation is inferred. Full methods, figures and strain provenance remain unread.
DOI:10.1016/s0143-4160(98)90030-6
This is a detailed characterization of a secretory mutant incapable of releasing secretory contents despite normal exocytotic membrane fusion performance.

PMID:9681197. Scientific Abstract verified in PubMed XML and Europe PMC metadata. Relevant Methods, Results and Discussion were read in the primary PDF at https://d-nb.info/1107191386/34; pages 349-350 and 354-356, including Figures 6-9, were visually inspected. Paramecium caudatum tnd1 retains condensed cargo despite fusion and extracellular fluorochrome access. Figure 9 shows untriggered mutant cells, not a wildtype experiment. This supports separation of fusion and discharge, not tnd1 as a positive example of completed secretion. Reduced calcium binding is a proposed explanation, not a proven molecular lesion. Other figures and tables were not visually audited.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1083/jcb.56.1.153

Parent traits (1)

phenotype METPO:1000059

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Discussions and Knowledge Gaps (2)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Separate the secretion phenotype from its component steps.

CURATION TODO OPEN exocytosis-scope-and-mapping · raised by codex · 2026-10-06

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

This concerns secretion by the microbe, not a host-cell response. Docking, intracellular trafficking or fusion alone does not demonstrate cargo release. Transporter-mediated export, membrane budding, lysis, cell-cell fusion and endocytosis are not equivalents. Constitutive and stimulus-regulated secretion are included; total emptying, permanent vesicle collapse and a shared calcium response are not required. GO:0006887 was resolved at https://www.ebi.ac.uk/QuickGO/services/ontology/go/terms/GO%3A0006887 and includes partial secretion through transient pores, but denotes a biological process rather than an equivalent organismal phenotype. No xref or synonym is inferred. The obsolete METPO secretion classes are broader, not exact replacements or usable parents. Retain phenotype METPO:1000059 pending human mapping review.

Resolve natural strain provenance and route-specific mechanisms.

KNOWLEDGE GAP OPEN exocytosis-exemplar-and-mechanism · raised by codex · 2026-10-06

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Canonical examples remain unset: the historical Tetrahymena strain needs modern taxonomy and provenance review, the yeast experiment uses conditional sec mutants, and the origin of the Paramecium tnd1 mutant has not been independently checked. Do not infer natural or engineered provenance from a mutant label. The fusion-only mutant is boundary evidence, not a positive secretion exemplar. These studies support phenotype scope across experimental systems, not one conserved protein mechanism. Obtain taxon-paired functional evidence and verified accessions before adding protein examples or a causal graph.

Curation history

2026-10-06T08:06:46Z · MINTED_TRAITMECH_ID · codex
Added exocytosis with three DOI-backed scientific-abstract snippets and explicit secretion-versus-fusion, strain and source-access limits. Ignored-and-hidden searches and pinned METPO review found no exact record. Reserved METPO:1059000 in v513. Deferred unverified examples, mappings and protein mechanisms; no existing trait was reparented.