Caspase 12 is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that in humans is encoded by the ''CASP12''

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

. The protein belongs to a family of

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

s called caspases which cleave their substrates at

C-terminal The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...

aspartic acid residues. It is closely related to

caspase 1 Caspase-1/Interleukin-1 converting enzyme (ICE) is an evolutionarily conserved enzyme that proteolytically cleaves other proteins, such as the precursors of the inflammatory cytokines interleukin 1β and interleukin 18 as well as the pyroptosi ...

and other members of the caspase family, known as inflammatory caspases, which process and activate inflammatory

cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

s such as

interleukin 1 The Interleukin-1 family (IL-1 family) is a group of 11 cytokines that plays a central role in the regulation of immune and inflammatory responses to infections or sterile insults. Discovery Discovery of these cytokines began with studies on t ...

and

interleukin 18 Interleukin-18 (IL-18), also known as interferon-gamma inducing factor) is a protein which in humans is encoded by the ''IL18'' gene. The protein encoded by this gene is a proinflammatory cytokine. Many cell types, both hematopoietic cells and non ...

Gene

It is found on

chromosome 11 Chromosome 11 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome. Chromosome 11 spans about 135 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the tot ...

in humans in a

locus Locus (plural loci) is Latin for "place". It may refer to: Entertainment * Locus (comics), a Marvel Comics mutant villainess, a member of the Mutant Liberation Front * ''Locus'' (magazine), science fiction and fantasy magazine ** ''Locus Award' ...

with other inflammatory caspases. ''CASP12''

orthologs Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a sp ...

have been identified in numerous mammals for which complete genome data are available.

Clinical significance

The CASP12

is subject to polymorphism, which can generate a full-length caspase protein (Csp12L) or an inactive truncated form (Csp12S). The functional form appears to be confined to people of African descent and is linked with susceptibility to

sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...

; people carrying the functional gene have decreased responses to bacterial molecules such as

lipopolysaccharide Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer ...

(LPS). A study in May 2009 by McGill University Health Centre has suggested that

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

may serve to block the production of caspase-12, resulting in a stronger inflammatory reaction to bacterial pathogens. The trials were carried out on laboratory mice which had been implanted with the human caspase-12 gene. The inactive truncated form (Csp12S) of the CASP12

was spread and nearly fixed in non-African populations due to positive selection beginning perhaps 60–100 thousand years ago. Its selective advantage is thought to be sepsis resistance in populations that experienced more infectious diseases as population sizes and densities increased.

References

External links

* The

MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibit ...

online database for peptidases and their inhibitors
C14.013
{{Portal bar, Biology, border=no EC 3.4.22 Caspases