Ecto-phospholipase that cleaves the phosphodiester bond in the glycosylphosphatidylinositol (GPI) anchor of various proteins, releasing them from the plasma membrane into the extracellular space (PubMed:27693046, PubMed:31932507, PubMed:33731436). Cleaves the GPI- anchor of glypican-6/GPC6, thereby positively regulating neuron differentiation in a cell-autonomous manner (PubMed:27693046, PubMed:31932507). May also hydrolyze the GPI-anchor of glypican-3/GPC3 (PubMed:27693046). Cleaves the GPI-anchor of the serine protease inhibitor RECK, leading to its inactivation (PubMed:33731436). RECK inactivation inhibits NOTCH signaling in neighboring cells and induces differentiation of spinal motor neurons (By similarity). RECK inactivation can also regulate amyloid-beta precursor protein (APP) processing by ADAM10 (PubMed:33731436). May additionally catalyze the hydrolysis of the phosphodiester bond in sn-glycerol 3-phosphocholine, potentially contributing to osmotic regulation of cellular glycerophosphocholine levels (By similarity). {ECO:0000250|UniProtKB:Q3KTM2, ECO:0000250|UniProtKB:Q640M6, ECO:0000269|PubMed:27693046, ECO:0000269|PubMed:31932507, ECO:0000269|PubMed:33731436}. This is the function of ENSG00000158555 (GDPD5, glycerophosphodiester phosphodiesterase domain containing 5).