Plays a central role in autophagy (PubMed:10604474, PubMed:12372286, PubMed:19270693, PubMed:28445460). Acts as core subunit of different PI3K complex forms that mediate formation of phosphatidylinositol 3-phosphate and are believed to play a role in multiple membrane trafficking pathways: PI3KC3-C1 is involved in initiation of autophagosomes and PI3KC3-C2 in maturation of autophagosomes and endocytosis (PubMed:19270693, PubMed:25275521). Involved in regulation of degradative endocytic trafficking and required for the abcission step in cytokinesis, probably in the context of PI3KC3-C2 (By similarity). Essential for the formation of PI3KC3-C2 but not PI3KC3-C1 PI3K complex forms (PubMed:25275521). Involved in endocytosis including endosome formation in neuronal cells (PubMed:25275521). May play a role in antiviral host defense (By similarity).

Beclin-1-C 35 kDa localized to mitochondria can promote apoptosis; it induces the mitochondrial translocation of BAX and the release of proapoptotic factors (By similarity).