early endosome

GO:0005769 · Membrane organelle · Membrane bounded organelle · Proposed

A membrane-bounded organelle that receives incoming material from primary endocytic vesicles that have been generated by clathrin-dependent and clathrin-independent endocytosis; vesicles fuse with the early endosome to deliver cargo for sorting into recycling or degradation pathways. [GO:0005769]

Has part: early endosome membrane (GO:0031901); early endosome lumen (GO:0031905)

Xrefs: uniprot.location:SL-0094 — Early endosome

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
early endosome membrane	Lipid	part of	`GO:0031901`			ESSENTIAL	Lipid-bilayer boundary that encloses the early endosome lumen and receives endocytic vesicles for cargo sorting. `GO:0031901` GO:0031901 identifies the lipid bilayer surrounding an early endosome. `GO:0005769` GO:0005769 defines the early endosome as a membrane-bounded organelle that receives cargo from primary endocytic vesicles.

Taxonomic distribution

NCBITaxon:5693 Trypanosoma cruzi — VARIABLE: Trypanosoma cruzi epimastigotes use an early endosomal network between cytostome entry and reservosome storage. [DOI:10.1078/0171-9335-00112]

Canonical examples

NCBITaxon:5693 Trypanosoma cruzi — Kinetoplastid parasite whose epimastigote endocytic cargo was traced from the cytostome through an early endosomal network to posterior reservosomes. [DOI:10.1078/0171-9335-00112]

Functions

early endosome endocytic cargo sorting — Early endosomes receive material from newly formed endocytic vesicles and sort cargo toward recycling or degradation routes.
- GO:0005769 GO:0005769 defines early endosomes as receiving incoming material from primary endocytic vesicles for sorting toward recycling or degradation pathways.
- DOI:10.1078/0171-9335-00112 Porto-Carreiro et al. 2000 traced Trypanosoma cruzi endocytic cargo through an early endosomal network before it reached reservosomes.

Mechanism graphs

Early endosome topology and cargo sorting (FUNCTION)

The early endosome membrane bounds a lumenal compartment that receives internalized cargo moving through the endocytic pathway.

Subject	Predicate	Object	Evidence
early endosome	is a	endosome	`GO:0005769` GO:0005769 identifies early endosomes as endosomes.
early endosome membrane	is part of	early endosome	`GO:0031901` GO:0031901 identifies the lipid bilayer surrounding an early endosome.
early endosome lumen	is part of	early endosome	`GO:0031905` GO:0031905 defines the early endosome lumen as the volume enclosed by the membrane of an early endosome.
early endosome membrane	bounds	early endosome lumen	`GO:0031901` GO:0031901 identifies the early endosome membrane. `GO:0031905` GO:0031905 defines the early endosome lumen by enclosure within the membrane of an early endosome.
cytostome	admits	endocytic cargo	`DOI:10.1078/0171-9335-00112` Porto-Carreiro et al. 2000 traced cargo entry through the cytostome in T. cruzi epimastigotes.
endocytic cargo	passes through	early endosome	`DOI:10.1078/0171-9335-00112` Porto-Carreiro et al. 2000 placed an early endosomal network between cytostome entry and reservosome storage.
endocytic cargo	accumulates in	reservosome	`DOI:10.1078/0171-9335-00112` Porto-Carreiro et al. 2000 followed endocytic cargo into posterior T. cruzi reservosomes.

Discussions

INTERPRETATION (RESOLVED): Model the Trypanosoma reservosome as a separate downstream organelle rather than as an early-endosome subtype. Porto-Carreiro et al. 2000 placed the early endosomal network upstream of posterior reservosome storage in T. cruzi epimastigotes, so this record keeps the generic GO:0005769 early-endosome identity distinct from the minted reservosome record.

Evidence

GO:0005769 Gene Ontology cellular-component term for the early endosome.
GO:0005768 Gene Ontology cellular-component parent term for endosomes.
GO:0031901 Gene Ontology cellular-component term for the early endosome membrane.
GO:0031905 Gene Ontology cellular-component term for the early endosome lumen.
GO:0031910 Gene Ontology cellular-component term for the cytostome.
uniprot.location:SL-0094 — Early endosome UniProt Subcellular Location entry SL-0094 maps Early endosome to GO:0005769.
DOI:10.1078/0171-9335-00112 Porto-Carreiro et al. 2000, Trypanosoma cruzi epimastigote endocytic pathway: cargo enters the cytostome and passes through an early endosomal network before storage in reservosomes, European Journal of Cell Biology.

Curation history

2026-09-22T16:15:39Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-22T16:16:23Z codex · EXPANDED_RECORD — Added endosome parentage, early-endosome membrane and lumen parts, UniProt SL-0094 xref, a GO-grounded membrane component, Trypanosoma cruzi epimastigote scope, endocytic cargo-sorting function, GO/UniProt/DOI evidence, a nonmechanistic topology and cargo-route graph, and a resolved reservosome-boundary discussion.
2026-09-22T16:28:08Z codex · ADDRESSED_PR_REVIEW — Addressed PR #1299 review issues #1300 and #1301 by narrowing graph scope notes to T. cruzi and removing the local reservosome record ID from discussion evidence.

Source: data/structures/membrane_organelle/early_endosome.yaml