Lysophospholipid receptor
Encyclopedia
The lysophospholipid receptor (LPL-R) group are members of the G protein-coupled receptor
family of integral membrane protein
s that are important for lipid signaling
. In humans, there are eight LPL receptors, each encoded by a separate gene. These LPL receptor genes are also sometimes referred to as "Edg” (an acronym for endothelial differentiation gene).
, lysophosphatidic acid
(LPA) and sphingosine 1-phosphate (S1P).
that is missing one of its two O-acyl chains
. Thus, LPLs have a free alcohol in either the sn-1 or the sn-2 position. The prefix 'lyso-' comes from the fact that lysophospholipids were originally found to be hemolytic, however it is now used to refer generally to phospholipids missing an acyl chain. LPLs are usually the result of phospholipase A
-type enzymatic activity on regular phospholipids such as phosphatidylcholine
or phosphatidic acid, although they can also be generated by the acylation of glycerophospholipids or the phosphorylation of monoacylglycerols. Some LPLs serve important signaling functions such as lysophosphatidic acid
.
receptors located in the cell membrane. Depending on which ligand, receptor, and cell type is involved, the activated receptor can have a range of effects on the cell. These include primary effects of inhibition of adenylyl cyclase and release of calcium
from the endoplasmic reticulum
, as well as secondary effects of preventing apoptosis
and increasing cell proliferation.
G protein-coupled receptor
G protein-coupled receptors , also known as seven-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors , comprise a large protein family of transmembrane receptors that sense molecules outside the cell and activate inside signal...
family of integral membrane protein
Integral membrane protein
An integral membrane protein is a protein molecule that is permanently attached to the biological membrane. Proteins that cross the membrane are surrounded by "annular" lipids, which are defined as lipids that are in direct contact with a membrane protein...
s that are important for lipid signaling
Lipid signaling
Lipid signaling, broadly defined, refers to any biological signaling event involving a lipid messenger that binds a protein target, such as a receptor, kinase or phosphatase, which in turn mediate the effects of these lipids on specific cellular responses...
. In humans, there are eight LPL receptors, each encoded by a separate gene. These LPL receptor genes are also sometimes referred to as "Edg” (an acronym for endothelial differentiation gene).
Ligands
The ligands for LPL-R group are the lysophospholipid extracellular signaling moleculesLipid signaling
Lipid signaling, broadly defined, refers to any biological signaling event involving a lipid messenger that binds a protein target, such as a receptor, kinase or phosphatase, which in turn mediate the effects of these lipids on specific cellular responses...
, lysophosphatidic acid
Lysophosphatidic acid
Lysophosphatidic acid is a phospholipid derivative that can act as a signaling molecule.-Function:LPA acts as a potent mitogen due to its activation of three high-affinity G-protein-coupled receptors called LPA1, LPA2, and LPA3...
(LPA) and sphingosine 1-phosphate (S1P).
Origin of name
The term lysophospholipid (LPL) refers to any phospholipidPhospholipid
Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from...
that is missing one of its two O-acyl chains
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
. Thus, LPLs have a free alcohol in either the sn-1 or the sn-2 position. The prefix 'lyso-' comes from the fact that lysophospholipids were originally found to be hemolytic, however it is now used to refer generally to phospholipids missing an acyl chain. LPLs are usually the result of phospholipase A
Phospholipase A
Phospholipase A can refer to:* Phospholipase A1* Phospholipase A2An enzyme that displays both phospholipase A1 and phospholipase A2 activities is called a Phospholipase B ....
-type enzymatic activity on regular phospholipids such as phosphatidylcholine
Phosphatidylcholine
Phosphatidylcholines are a class of phospholipids that incorporate choline as a headgroup.They are a major component of biological membranes and can be easily obtained from a variety of readily available sources such as egg yolk or soy beans from which they are mechanically extracted or chemically...
or phosphatidic acid, although they can also be generated by the acylation of glycerophospholipids or the phosphorylation of monoacylglycerols. Some LPLs serve important signaling functions such as lysophosphatidic acid
Lysophosphatidic acid
Lysophosphatidic acid is a phospholipid derivative that can act as a signaling molecule.-Function:LPA acts as a potent mitogen due to its activation of three high-affinity G-protein-coupled receptors called LPA1, LPA2, and LPA3...
.
Function
LPL receptor ligands bind to and activate their cognateCognate
In linguistics, cognates are words that have a common etymological origin. This learned term derives from the Latin cognatus . Cognates within the same language are called doublets. Strictly speaking, loanwords from another language are usually not meant by the term, e.g...
receptors located in the cell membrane. Depending on which ligand, receptor, and cell type is involved, the activated receptor can have a range of effects on the cell. These include primary effects of inhibition of adenylyl cyclase and release of calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
from the endoplasmic reticulum
Endoplasmic reticulum
The endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...
, as well as secondary effects of preventing apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
and increasing cell proliferation.
Group members
The following is a list of the eight known human LPL receptors:| Gene Symbol | IUPHAR Symbol | Gene / Protein Name | Agonist Ligand | Synonyms |
|---|---|---|---|---|
| LPAR1 | lysophosphatidic acid receptor 1 | LPA | EDG2 | |
| LPAR2 | lysophosphatidic acid receptor 2 | " | EDG4 | |
| LPAR3 | lysophosphatidic acid receptor 3 | " | EDG7 | |
| LPAR4 | LPA4 | lysophosphatidic acid receptor 4 | " | GPR23 |
| LPAR5 | LPA5 | lysophosphatidic acid receptor 5 | " | GPR92 |
| LPAR6 | LPA6 | lysophosphatidic acid receptor 6 | " | P2RY5 |
| S1PR1 | sphingosine-1-phosphate receptor 1 | S1P | EDG1 | |
| S1PR2 | sphingosine-1-phosphate receptor 2 | " | EDG5 | |
| S1PR3 | sphingosine-1-phosphate receptor 3 | " | EDG3 | |
| S1PR4 | sphingosine-1-phosphate receptor 4 | " | EDG6 | |
| S1PR5 | sphingosine-1-phosphate receptor 5 | " | EDG8 |