Prokineticin receptor 2 (PKR₂), is a dimeric

G protein-coupled receptor G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related ...

encoded by the PROKR2

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

in humans.

Function

Prokineticins are secreted proteins that can promote angiogenesis and induce strong gastrointestinal smooth muscle contraction. The protein encoded by this gene is an integral membrane protein and G protein-coupled receptor for prokineticins. PKR₂ is composed of 384 amino acids. Asparagine residues at position 7 and 27 undergo

N-linked glycosylation ''N''-linked glycosylation is the attachment of an oligosaccharide, a carbohydrate consisting of several sugar molecules, sometimes also referred to as glycan, to a nitrogen atom (the amide nitrogen of an asparagine (Asn) residue of a protein), i ...

. Cysteine residues at position 128 and 208 form a

disulfide bond In chemistry, a disulfide (or disulphide in British English) is a compound containing a functional group or the anion. The linkage is also called an SS-bond or sometimes a disulfide bridge and usually derived from two thiol groups. In inor ...

. The encoded protein is similar in sequence to GPR73, another G protein-coupled receptor for prokineticins. PKR₂ is also linked to mammalian circadian rhythm. Levels of PKR₂

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

fluctuate in the

suprachiasmatic nucleus The suprachiasmatic nucleus or nuclei (SCN) is a small region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for regulating sleep cycles in animals. Reception of light inputs from photosensitive r ...

, increasing during the day and decreasing at night.

Mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...

s in the ''PROKR2'' (also known as ''KAL3'')

have been implicated in

hypogonadotropic hypogonadism Hypogonadotropic hypogonadism (HH), is due to problems with either the hypothalamus or pituitary gland affecting the hypothalamic-pituitary-gonadal axis (HPG axis). Hypothalamic disorders result from a deficiency in the release of gonadotropic ...

and

gynecomastia Gynecomastia (also spelled gynaecomastia) is the non-cancerous enlargement of one or both breasts in men due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Updated by Brent Wisse (10 Novemb ...

. Total loss of PKR₂ in mice leads to spontaneous

torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the ti ...

usually beginning at dusk and lasting for 8 hours on average. PKR₂ functions as a G protein-coupled receptor, thus it has a signaling cascade when it's

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

binds. PKR₂ is a Gq-coupled protein, so when the ligand binds, beta-type phospholipase C is activated which creates

inositol triphosphate Inositol trisphosphate or inositol 1,4,5-trisphosphate abbreviated InsP3 or Ins3P or IP3 is an inositol phosphate signaling molecule. It is made by hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), a phospholipid that is located in the p ...

. This then triggers calcium release inside the cell.

References

External links

GeneReviews/NCBI/NIH/UW entry on Kallmann syndrome
* {{G protein-coupled receptors G protein-coupled receptors

Function

See also

References

Further reading

External links