Regulator for autophaosome formation and/or maturation (PubMed:24249832, Ref.9). Binds phosphatidylinositol-phosphate; highest affinity for vesicles containing PtdIns(3,4,5)P(3), followed by those containing PtdIns(4,5)P(2) and PtdIns(3,4)P(2), with minimal binding to phosphatidylinositol monophosphates, including PtdIns(3)P (PubMed:24249832, PubMed:28584166). Together with DRP1A, converts the fused vesicles to tubular structures at the cell plate during cytokinesis (PubMed:28584166). Homodimer (PubMed:24249832, PubMed:28584166). Interacts with FREE1 (PubMed:25699591, PubMed:25624505). Interacts (via SH3 domain) with ATG8E and ATG8F (PubMed:24249832). Component of a phosphoinositide 3-kinase (PI3K) complex containing ATG6, SH3P2 and FREE1 (PubMed:25624505, PubMed:24249832). Binds to SH3P3 and DRP1A (PubMed:28584166). Forms a complex made of SH3P2 and DRP1A and triggers its accumulation at the cell plate (PubMed:28584166). Transolcate from the cytosol to the phagophore assembly site/preautophagosome structure upon autophagy induction (PubMed:24249832). Localized at the leading edge of the cell plate in dividing cells, especially in constricted or curved regions (PubMed:28584166). Observed at the plasma membrane and in endosomal compartments in non-dividing cells (PubMed:28584166). Highly expressed in seedlings. Detected in flowers, leaves and stems. The N-terminal BAR domain is required for the interaction with FREE1. Delayed germination, but almost normal growth after germination in sh3p2 partial mutants (PubMed:28584166). RNAi plants exhibit cytokinesis-defective phenotypes associated with the aggregation of vesicles at the leading edge of the cell plate and abnormal cytosolic localization of DRP1A in dividing cells (PubMed:28584166). Knockdown of SH3P2 is developmentally lethal and significantly suppresses autophagosome formation.