Interleukin 34 (IL-34) is a
protein belonging to a group of
cytokines called
interleukins. It was originally identified in humans, by large scale screening of
secreted proteins; chimpanzee, murine, rat and chicken interleukin 34
orthologs have also been found. The protein is composed of 241
amino acids, 39
kilodaltons
The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass widely used in physics and chemistry. It is defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at ...
in mass, and forms
homodimers
In biochemistry, a protein dimer is a macromolecular complex formed by two protein monomers, or single proteins, which are usually non-covalently bound. Many macromolecules, such as proteins or nucleic acids, form dimers. The word ''dimer'' has ...
. IL-34 increases growth or survival of immune cells known as
monocytes; it elicits its activity by binding the
Colony stimulating factor 1 receptor.
Messenger RNA
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 synthesizing a protein.
mRNA is created during the p ...
(mRNA) expression of human IL-34 is most abundant in
spleen but occurs in several other tissues:
thymus,
liver,
small intestine
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the p ...
,
colon,
prostate gland,
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
,
heart,
brain,
kidney,
testes, and
ovary
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...
. The discovery of IL-34 protein in the
red pulp
The red pulp of the spleen is composed of connective tissue known also as the cords of Billroth and many splenic sinusoids that are engorged with blood, giving it a red color. Its primary function is to filter the blood of antigens, microorgani ...
of the spleen suggests involvement in growth and development of
myeloid cell
A myelocyte is a young cell of the granulocytic series, occurring normally in bone marrow (can be found in circulating blood when caused by certain diseases).
Structure
When stained with the usual dyes, the cytoplasm is distinctly basophilic ...
s, consistent with its activity on monocytes.
References
External links
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Interleukins
Signal transduction
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