Phosphatase Superfamily AP
Alkaline phosphatases are found in metazoa, fungi, some protists, and bacteria, but are absent from most plants. They belong to the alkaline phosphatase-like fold (SCOP), which contains other enzymes, such as phosphoesterases and sulfatases.
Alkaline phosphatases are a superfamily (Pfam) with a wide variety of substrates, possibly including phosphoproteins. There are four human alkaline phosphatases, named by their tissue expression: ALPI (alkaline phosphatase, intestinal), ALPP (alkaline phosphatase, placental), ALPPL2 (alkaline phosphatase, placental-like 2), and ALPL (alkaline phosphatase, liver/bone/kidneytissue). Early reports found that ALPL and ALPI can dephosphorylate Histone H2A [1, 2] and that PLAP is a protein tyrosine phosphatase , but their physiological relevance as protein phosphatases is still unclear.
- Swarup G, Cohen S, and Garbers DL. Selective dephosphorylation of proteins containing phosphotyrosine by alkaline phosphatases. J Biol Chem. 1981 Aug 10;256(15):8197-201.
- Chan JR and Stinson RA. Dephosphorylation of phosphoproteins of human liver plasma membranes by endogenous and purified liver alkaline phosphatases. J Biol Chem. 1986 Jun 15;261(17):7635-9.
- Telfer JF and Green CD. Placental alkaline phosphatase activity is inversely related to cell growth rate in HeLaS3 cervical cancer cells. FEBS Lett. 1993 Aug 30;329(3):238-44.