Alkaline phosphatase (ALPL) is a hydrolase enzyme responsible for removing phosphate groups from many types of molecules, including nucleotides, proteins, and alkaloids. As the name suggests, alkaline phosphatase is most effective in an alkaline environment.
Alkaline phosphatases (APs) are ubiquitous in many species from bacteria to human. Four genes encode AP isoenzymes in humans and rodents. Three AP genes are expressed in a tissue-specific manner (i.e., placental, embryonic, and intestinal AP isoenzymes). Expression of the fourth AP gene is nonspecific to a single tissue and is particularly abundant in bone, liver, and kidney. This isoenzyme is also known as tissue-nonspecific alkaline phosphatase (TNAP).
