Phosphatase that has a high activity toward phosphoethanolamine (PEA) and phosphocholine (PCho) . Involved in the generation of inorganic phosphate for bone mineralization (By similarity). Acts in a non-redundant manner with PHOSPHO1 in skeletal mineralization: while PHOSPHO1 mediates the initiation of hydroxyapatite crystallization in the matrix vesicles (MVs), ALPL/TNAP catalyzes the spread of hydroxyapatite crystallization in the extracellular matrix (By similarity).
Subcellular locations: Extracellular vesicle
Localizes to special class of extracellular vesicles, named matrix vesicles (MVs), which are released by osteogenic cells.
Expressed at sites of mineralization in bone and cartilage. Highly expressed in osteoblast cell line SaOS-2 which produces a mineralized matrix, but not in MG-63 cell line, which do not mineralize.