identifier: traitmech:000637
label: exocytosis
definition: 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.
definition_source: DOI:10.1083/jcb.56.1.153
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1083/jcb.56.1.153
  snippet: The cytoplasm between the two matching membrane sites is squeezed away
    and the membranes fuse
  notes: 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.
- reference: DOI:10.1007/BF01870409
  snippet: Upon returning the cells to the permissive temperature the contents of
    the accumulated vesicles were secreted.
  notes: 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.
- reference: DOI:10.1016/s0143-4160(98)90030-6
  snippet: This is a detailed characterization of a secretory mutant incapable of
    releasing secretory contents despite normal exocytotic membrane fusion performance.
  notes: 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.
discussions:
- discussion_id: exocytosis-scope-and-mapping
  prompt: Separate the secretion phenotype from its component steps.
  kind: CURATION_TODO
  status: OPEN
  rationale: 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.
  posed_by: codex
  posed_date: '2026-10-06'
- discussion_id: exocytosis-exemplar-and-mechanism
  prompt: Resolve natural strain provenance and route-specific mechanisms.
  kind: KNOWLEDGE_GAP
  status: OPEN
  rationale: '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.'
  posed_by: codex
  posed_date: '2026-10-06'
curation_history:
- timestamp: '2026-10-06T08:06:46Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: 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.
  llm_assisted: true