Formyl peptide receptor

Last updated
formyl peptide receptor 1
Identifiers
SymbolFPR1
Alt. symbolsFPR; FMLP
NCBI gene 2357
HGNC 3826
OMIM 136537
RefSeq NM_002029
UniProt P21462
Other data
Locus Chr. 19 q13.41
Search for
Structures Swiss-model
Domains InterPro
formyl peptide receptor 2
Identifiers
SymbolFPR2
Alt. symbolsALXR, FMLPX, FPR2/ALX, FPR2A, FPRH1, FPRL1, HM63, LXA4R, RFP
NCBI gene 2358
HGNC 3827
OMIM 136538
RefSeq NM_001462
UniProt P25090
Other data
Locus Chr. 19 q13.3-13.4
Search for
Structures Swiss-model
Domains InterPro
formyl peptide receptor 3
Identifiers
SymbolFPR3
Alt. symbolsFPRH2, FPRL2, FMLPY
NCBI gene 2359
HGNC 3828
OMIM 136539
RefSeq NM_002030
UniProt P25089
Other data
Locus Chr. 19 q13.3-13.4
Search for
Structures Swiss-model
Domains InterPro

The formyl peptide receptors (FPR) belong to a class of G protein-coupled receptors involved in chemotaxis. [1] [2] In humans, there are three formyl peptide receptor isoforms, each encoded by a separate gene that are named FPR1, FPR2, and FPR3. [1] These receptors were originally identified by their ability to bind N-formyl peptides such as N-formylmethionine produced by the degradation of either bacterial or host cells. [3] [4] Hence formyl peptide receptors are involved in mediating immune cell response to infection. These receptors may also act to suppress the immune system under certain conditions. [5] The close phylogenetic relation of signaling in chemotaxis and olfaction was recently proved by detection formyl peptide receptor like proteins as a distinct family of vomeronasal organ chemosensors in mice. [6] [7]

Contents

FPR is now properly accepted as termed FPR1 by the International Union of Basic and Clinical Pharmacology. [2]

Discovery

Studies conducted in the 1970s found that a series of N-Formylmethionine-containing oligopeptides, including the most potent and best known member of this series, N-formylmethionine-leucyl-phenylalanine (fMLF or fMet-Leu-Phe), stimulated rabbit and human neutrophils by an apparent receptor-dependent mechanism to migrate in a directional pattern in classical laboratory assays of chemotaxis. Since these oligopeptides were produced by bacteria or synthetic analogs of such products, it was suggested that the N-formyl oligopeptides are important chemotatic factors and their receptors are important chemotactic factor receptors that act respectively as signaling and signal-recognizing elements to initiate inflammation responses in order to defend against bacterial invasion. Further studies defined a receptor for the N-formyl oligopeptides, formyl peptide receptor (FPR), so named based on its ability to bind and become activated by the oligopeptides. Two receptors where thereafter discovered and named FPR1 and FPR2 based on the similarity of their genes' predicted amino acid sequence to that of FPR rather than on any ability to bind or be activated by the formyl oligopeptides. These three receptors have been renamed as FPR1, FPR2, and FPR3 and found to have very different specificities for the formyl oligopeptides and very different functions that include initiating inflammatory responses to N-formyl peptides released not only by bacteria but also a multiplicity of elements released by host tissues; dampening and resolving inflammatory responses; and perhaps contributing to the development of certain neurological cancers and an array of neurological diseases Amyloid-based diseases. [2]

Structure and function

The formyl peptide receptor (FPR) belongs to the class of receptors possessing seven hydrophobic transmembrane domains. The conformation of the FPR is stabilized by several interactions. These include potential salt bridge formation between Arg84-Arg205, Lys85-Arg205, and Lys85-Asp284 which help determine the three-dimensional structure of transmembrane domains, as well as positively charged residues (Arg, Lys) which interact with negatively charged phosphates. Furthermore, residue Arg163 may interact with the ligand binding pocket of the second extracellular loop of the FPR.

With respect to binding of the formyl Met-Leu-Phe peptide, there are additional potential interactions which include hydrogen bonding interactions between Arg84 and Lys85 of the first extracellular loop and the N-formyl group of the ligand as well as the peptide backbone of formyl Met-Leu-Phe which can form similar interactions. The formyl-Met moiety of the ligand was shown to form disulfide bridges with Cys residues, and an interaction with Arg163 was also demonstrated. (It is important to mention that some interaction which stabilize the conformation of the receptor may also influence ligand-binding.) Some oligopeptides were also described as characteristic constituents linked to Asn-s of the extracellular N terminal part and to the ligand binding pocket of the second extracellular loop. These components can also determine or make more specific the ligand-receptor interaction. [7] [8]

Signaling pathways

Induction of FPR triggers multiple changes in eukaryotic cells including rearrangement of the cytoskeleton which in turn facilitates cell migration and the synthesis of chemokines. Important FPR regulated pathways include:

See also

Related Research Articles

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<span class="mw-page-title-main">Protein kinase</span> Enzyme that adds phosphate groups to other proteins

A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a functional change of the target protein (substrate) by changing enzyme activity, cellular location, or association with other proteins. The human genome contains about 500 protein kinase genes and they constitute about 2% of all human genes. There are two main types of protein kinase. The great majority are serine/threonine kinases, which phosphorylate the hydroxyl groups of serines and threonines in their targets. Most of the others are tyrosine kinases, although additional types exist. Protein kinases are also found in bacteria and plants. Up to 30% of all human proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction.

<span class="mw-page-title-main">Signal transduction</span> Cascade of intracellular and molecular events for transmission/amplification of signals

Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. Most commonly, protein phosphorylation is catalyzed by protein kinases, ultimately resulting in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway.

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Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers. Second messengers trigger physiological changes at cellular level such as proliferation, differentiation, migration, survival, apoptosis and depolarization.

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<i>N</i>-Formylmethionine Chemical compound

N-Formylmethionine is a derivative of the amino acid methionine in which a formyl group has been added to the amino group. It is specifically used for initiation of protein synthesis from bacterial and organellar genes, and may be removed post-translationally.

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<span class="mw-page-title-main">Formyl peptide receptor 2</span> Protein-coding gene in the species Homo sapiens

N-formyl peptide receptor 2 (FPR2) is a G-protein coupled receptor (GPCR) located on the surface of many cell types of various animal species. The human receptor protein is encoded by the FPR2 gene and is activated to regulate cell function by binding any one of a wide variety of ligands including not only certain N-Formylmethionine-containing oligopeptides such as N-Formylmethionine-leucyl-phenylalanine (FMLP) but also the polyunsaturated fatty acid metabolite of arachidonic acid, lipoxin A4 (LXA4). Because of its interaction with lipoxin A4, FPR2 is also commonly named the ALX/FPR2 or just ALX receptor.

<i>N</i>-Formylmethionine-leucyl-phenylalanine Chemical compound

N-Formylmethionyl-leucyl-phenylalanine is an N-formylated tripeptide and sometimes simply referred to as chemotactic peptide is a potent polymorphonuclear leukocyte (PMN) chemotactic factor and is also a macrophage activator.

<span class="mw-page-title-main">Formyl peptide receptor 3</span> Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">Formyl peptide receptor 1</span> Protein-coding gene in the species Homo sapiens

Formyl peptide receptor 1 is a cell surface receptor protein that in humans is encoded by the formyl peptide receptor 1 (FPR1) gene. This gene encodes a G protein-coupled receptor cell surface protein that binds and is activated by N-Formylmethionine-containing oligopeptides, particularly N-Formylmethionine-leucyl-phenylalanine (FMLP). FPR1 is prominently expressed by mammalian phagocytic and blood leukocyte cells where it functions to mediate these cells' responses to the N-formylmethionine-containing oligopeptides which are released by invading microorganisms and injured tissues. FPR1 directs these cells to sites of invading pathogens or disrupted tissues and then stimulates these cells to kill the pathogens or to remove tissue debris; as such, it is an important component of the innate immune system that operates in host defense and damage control.

<span class="mw-page-title-main">Leucine-rich repeat receptor like protein kinase</span>

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References

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