Binds phospholipid vesicles containing phosphatidylinositol 3-phosphate and participates in endosomal trafficking. Homodimer. Binds STX6. Binds RAB5A, RAB5B, RAB5C and RAB22A that have been activated by GTP-binding. Interacts with RAB31. Interacts with ERBB2. Interacts with SAMD9 AND SAMD9L (PubMed:24029230). May interact with PLEKHF2. The FYVE-type zinc finger domain mediates interactions with phosphatidylinositol 3-phosphate in membranes of early endosomes and penetrates bilayers. The FYVE domain insertion into PtdIns(3)P-enriched membranes is substantially increased in acidic conditions. Antibodies against EEA1 are found in sera from patients with subacute cutaneous lupus erythematosus and other autoimmune diseases.