Metacaspases are related to caspases and paracaspase

Paracaspase

Paracaspases are related to caspases present in animals and slime mold, in contrast to metacaspases, which are present in plants, fungi, and "protists"....

. The metacaspases are Arginine

Arginine

Arginine is an α-amino acid. The L-form is one of the 20 most common natural amino acids. At the level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are the triplets of nucleotide bases or codons that codify for arginine during...

/Lysine

Lysine

Lysine is an α-amino acid with the chemical formula HO2CCH4NH2. It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG....

-specific, in contrast to caspases, which are Aspartate-specific. Metacaspases are found in plants, fungi, and "protists," but not in slime mold or animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s, with one recent exception where both type I and type II metacaspases were found in the genome of Monosiga brevicollis

Choanoflagellate

The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals...

, possibly as a result of an unusual horizontal gene transfer

Horizontal gene transfer

Horizontal gene transfer , also lateral gene transfer , is any process in which an organism incorporates genetic material from another organism without being the offspring of that organism...

 between two eukaryotes. In an analogous manner to caspases, metacaspases induce programmed cell death

Programmed cell death

Programmed cell-death is death of a cell in any form, mediated by an intracellular program. PCD is carried out in a regulated process which generally confers advantage during an organism's life-cycle...

 in both plants and fungi (yeast

Yeast

Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

).