Phosphatidate phosphatase

In enzymology, a phosphatidate phosphatase is an enzyme that catalyzes the chemical reaction:


 * a 3-sn-phosphatidate + H2O $$\rightleftharpoons$$ a 1,2-diacyl-sn-glycerol + phosphate

Thus, the two substrates of this enzyme are 3-sn-phosphatidate and H2O, whereas its two products are 1,2-diacyl-sn-glycerol and phosphate.

This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. This enzyme participates in 4 metabolic pathways: glycerolipid, glycerophospholipid, ether lipid, and sphingolipid metabolism.

Nomenclature
The systematic name of this enzyme class is 3-sn-phosphatidate phosphohydrolase. Other names in common use include:
 * phosphatidic acid phosphatase (PAP),
 * acid phosphatidyl phosphatase,
 * phosphatidic acid phosphohydrolase,
 * phosphatidate phosphohydrolase, and
 * lipid phosphate phosphohydrolase (LPP).

Types
There are several different genes that codify for phosphatidate phosphatases. They been classified in two groups (type I and type II) based on their cellular localization and substrate specificity.

Type I
Type I phosphatidate phosphatases are soluble enzymes that can associate to membranes. There are found mainly in the cytosol and the nucleus. Codified by a group of genes named Lipin they are substrate specific only to phosphatidate. There are speculated to be involved in the de novo synthesis of glycerolipids.

Type II
Type II phosphatidate phospatases are transmembrane enzymes found mainly in the plasma membrane. They can also dephosphorylate other substrates beside phosphatidate therefore are also known as lipid-phosphate phosphatase. Their main role is in lipid signaling and in phospholipid head-group remodeling.

Genes
Human genes that encode phosphatidate phosphatases include:
 * PPAP2A (LPP1) – phosphatidic acid phosphatase type 2A
 * PPAP2B (LPP3) – phosphatidic acid phosphatase type 2B
 * PPAP2C (LPP2) – phosphatidic acid phosphatase type 2C
 * PPAPDC1A (PPC1A) – phosphatidic acid phosphatase type 2 domain containing 1A
 * PPAPDC1B (PPC1B) – phosphatidic acid phosphatase type 2 domain containing 1B
 * PPAPDC2 – phosphatidic acid phosphatase type 2 domain containing 2
 * PPAPDC3 – phosphatidic acid phosphatase type 2 domain containing 3
 * LPPR2 – lipid phosphate phosphatase-related protein type 2
 * LPPR3 – lipid phosphate phosphatase-related protein type 3
 * LPPR4 – lipid phosphate phosphatase-related protein type 4
 * LPIN1 – lipin 1
 * LPIN2 – lipin 2
 * LPIN3 – lipin 3