Aspartyl proteases, also known as acid proteases, (EC 3.4.23.-) are a widely
distributed family of proteolytic enzymes [1,2,3] known to exist in
vertebrates, fungi, plants, retroviruses and some plant viruses. Aspartate
proteases of eukaryotes are monomeric enzymes which consist of two domains.
Each domain contains an active site centered on a catalytic aspartyl residue.
The two domains most probably evolved from the duplication of an ancestral
gene encoding a primordial domain. Currently known eukaryotic aspartyl
Vertebrate gastric pepsins A and C (also known as gastricsin).
Vertebrate chymosin (rennin), involved in digestion and used for making
Yeast saccharopepsin (EC 18.104.22.168) (proteinase A) (gene PEP4). PEP4 is
implicated in posttranslational regulation of vacuolar hydrolases.
Yeast barrierpepsin (EC 22.214.171.124) (gene BAR1); a protease that cleaves
α-factor and thus acts as an antagonist of the mating pheromone.
Fission yeast sxa1 which is involved in degrading or processing the mating
Most retroviruses and some plant viruses, such as badnaviruses, encode for an
aspartyl protease which is an homodimer of a chain of about 95 to 125 amino
acids. In most retroviruses, the protease is encoded as a segment of a
polyprotein which is cleaved during the maturation process of the virus. It
is generally part of the pol polyprotein and, more rarely, of the gag
Conservation of the sequence around the two aspartates of eukaryotic aspartyl
proteases and around the single active site of the viral proteases allows us
to develop a single signature pattern for both groups of protease. A profile
was developed to specifically detect viral aspartyl proteases, which are
missed by the pattern.
These proteins belong to families A1 and A2 in the classification of
December 2004 / Pattern and text revised.
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Gastric proteinases--structure, function, evolution and mechanism of action.
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