Human Alkaline phosphatases in health and disease: A mini review

Abstract

Distribution of Alkaline phosphatase (APase) is ubiquitous amongst different cell types and tissues in almost all living organisms. In mammals four isoenzymes with tissue-specific distribution have been well characterized. Several physiological functions have been proposed for APase. In bone, Tissue Non specific Alkaline Phosphatase (TNAPase) is thought to mediate phosphate assimilation. TNAPase may also play a role in the renal transport of phosphate. In the intestine, APase has been proposed to participate in the absorption and transport of lipids and nucleotides. Intestinal Alkaline phosphatase (IAPase) also function as a phosphate binding protein under physiological conditions in the brush border membrane vesicles. APases are abundantly expressed in tumor cells, and serum levels of APase isozymes are often used as tumor markers. Placental Alkaline phosphatase (PLAPase) and Germ cell Alkaline phosphatase (GCAPase) have been evaluated extensively in various malignant conditions. Structure and functions of different human APases along with their clinical significance are discussed in this communication.