Mediates the non-vesicular transport of glucosylceramide (GlcCer) from the trans-Golgi network (TGN) to the plasma membrane, playing a pivotal role in the synthesis of complex glycosphingolipids; binding of both phosphatidylinositol 4-phosphate (PIP) and ARF1 are essential for this GlcCer transfer ability (PubMed:15107860, PubMed:16103222, PubMed:17687330). Also functions as a cargo transport protein required for apical transport from the Golgi complex, including transport of AQP2 from the TGN to sites of AQP2 phosphorylation. Additionally required for primary cilium formation, possibly by being involved in the transport of raft lipids to the apical membrane, and for membrane tubulation (By similarity). {ECO:0000250|UniProtKB:D2KC46, ECO:0000269|PubMed:15107860, ECO:0000269|PubMed:16103222, ECO:0000269|PubMed:17687330}. This is the function of PLEKHA8 (pleckstrin homology domain containing A8, ENSG00000106086).