Plays a role in intracellular vesicle trafficking and exocytosis (PubMed:24843546). May play a role in maintaining insulin-containing dense core vesicles in pancreatic beta-cells and in preventing their degradation. May play a role in insulin secretion (PubMed:24843546). Interacts with membranes containing phosphatidylinositol 3-phosphate (PtdIns(3P)) (By similarity). Interacts with PTPRN. The PX domain mediates specific binding to membranes enriched in phosphatidylinositol 3-phosphate (PtdIns(P3)). Belongs to the sorting nexin family. Extended N-terminus.