Involved in the signaling of vulval development by acting as a negative regulator of epidermal growth factor receptor (EGFR) signaling. Aids in phagosomal membrane tubule formation which is required for phagosomal fusion with endosomes and lysosomes. Also recruits rab-7 to phagosomes by an interaction with dyn-1. These are events leading to phagosome maturation which is a step in apoptotic cell corpse clearance. Binds phosphatidylinositol-3,4,5-trisphosphate. Homodimer. Isoform d interacts (via SH3 domain) with dyn-1. Recruited to phagosomal surface by phosphatidylinositol trisphosphate. BAR and PX domains are required for the phagosomal localization. Expressed in vulval precursor cells (VPCs) and apoptotic germ cells. Colocalizes with actin, dyn-1 and rab-5 in early phagosomes. Highly expressed in all 6 vulval precursor cells (VPCs). At the time of inductive signaling, expression forms a gradient in response to inductive signal: expression is low in P6.p, intermediate in P5.p and P7.p and undiminished in P3.p, P4.p, and P8.p. Later, expression becomes strong again in P5.p and P7.p. The BAR and PX domains are required for recruitment to the phagosome. The SH3 domain is involved in phagosome maturation. Aberrant vulval development, ectopic vulval induction, retained cell corpses and defective recruitment of dyn-1 and rab-7 to phagosomal surfaces. Belongs to the sorting nexin family.